Answer: Taiwan

Context: On 5 June 2008, Secretary of Defense Robert Gates, accepted the resignations of both the Secretary of the Air Force, Michael Wynne, and the Chief of Staff of the United States Air Force, General T. Michael Moseley. Gates in effect fired both men for "systemic issues associated with declining Air Force nuclear mission focus and performance." This followed an investigation into two embarrassing incidents involving mishandling of nuclear weapons: specifically a nuclear weapons incident aboard a B-52 flight between Minot AFB and Barksdale AFB, and an accidental shipment of nuclear weapons components to Taiwan. The resignations were also the culmination of disputes between the Air Force leadership, populated primarily by non-nuclear background fighter pilots, versus Gates. To put more emphasis on nuclear assets, the USAF established the nuclear-focused Air Force Global Strike Command on 24 October 2008.

Question: Where did the US Air Force accidentally ship a component of Nuclear Weapons?


Answer: General T. Michael Moseley

Question: What US Chief of Staff of the US Air Force also resigned in June of 2008?


Answer: 24 October 2008

Question: When was the Air Force Global Strike Command formed?


Answer: Budget sequestration

Context: Due to the Budget sequestration in 2013, the USAF was forced to ground many of its squadrons. The Commander of Air Combat Command, General Mike Hostage indicated that the USAF must reduce its F-15 and F-16 fleets and eliminate platforms like the A-10 in order to focus on a fifth-generation jet fighter future. In response to squadron groundings and flight time reductions, many Air Force pilots have opted to resign from active duty and enter the Air Force Reserve and Air National Guard while pursuing careers in the commercial airlines where they can find flight hours on more modern aircraft.

Question: Why was the USAF forced to ground some of its squadrons in 2013?


Answer: General Mike Hostage

Question: Who was the Commander of Air Combat Command in 2013?


Answer: squadron groundings and flight time reductions

Question: Why have many US Air Force pilots opted to resign from active service?


Answer: careers in the commercial airlines

Question: Where have many of these US Air Force pilots chosen to find employment instead?


Answer: replace its aging fleet

Context: Specific concerns include a compounded inability for the Air Force to replace its aging fleet, and an overall reduction of strength and readiness. The USAF attempted to make these adjustments by primarily cutting the Air National Guard and Air Force Reserve aircraft fleets and their associated manpower, but Congress reversed this initiative and the majority of the lost manpower will come from the active forces. However, Congress did allow for $208 million of reprogramming from fleet modernization to enable some portion of the third of the grounded fleet to resume operations.

Question: What is one of the concerns of the Air Force?


Answer: cutting the Air National Guard and Air Force Reserve aircraft fleets

Question: How did the USAF try to make these adjustments to help with strength and readiness of its fleet?


Answer: $208 million

Question: How much money did Congress give to the USAF to enable them to replace some of the grounded fleet?


Answer: Secretary of the Air Force

Context: The Department of the Air Force is one of three military departments within the Department of Defense, and is managed by the civilian Secretary of the Air Force, under the authority, direction, and control of the Secretary of Defense. The senior officials in the Office of the Secretary are the Under Secretary of the Air Force, four Assistant Secretaries of the Air Force and the General Counsel, all of whom are appointed by the President with the advice and consent of the Senate. The senior uniformed leadership in the Air Staff is made up of the Chief of Staff of the Air Force and the Vice Chief of Staff of the Air Force.

Question: Who is the Department of the Air Force managed by?


Answer: Secretary of Defense

Question: Who does the Secretary of the Air Force report to?


Answer: President

Question: Who appoints the top positions in the USAF, including the Assistant Secretaries and General Council?


Answer: Senate

Question: Upon whom does the President call on for support in his appointments to the USAF?


Answer: Chief of Staff of the Air Force and the Vice Chief of Staff of the Air Force

Question: Who does the senior leadership roles in the USAF include?


Answer: Secretary of Defense

Context: The organizational structure as shown above is responsible for the peacetime organization, equipping, and training of aerospace units for operational missions. When required to support operational missions, the Secretary of Defense (SECDEF) directs the Secretary of the Air Force (SECAF) to execute a Change in Operational Control (CHOP) of these units from their administrative alignment to the operational command of a Regional Combatant Commander (CCDR). In the case of AFSPC, AFSOC, PACAF, and USAFE units, forces are normally employed in-place under their existing CCDR. Likewise, AMC forces operating in support roles retain their componency to USTRANSCOM unless chopped to a Regional CCDR.

Question: Who directs the Secretary of the Air Force during operational missions?


Answer: Change in Operational Control

Question: What does the abbreviation CHOP stand for?


Answer: USTRANSCOM

Question: Who does the AMC forces usually retain their componency to?


Answer: Regional Combatant Commander

Question: Who is in charge of these Change in Operational Control missions?


Answer: forces

Context: "Chopped" units are referred to as forces. The top-level structure of these forces is the Air and Space Expeditionary Task Force (AETF). The AETF is the Air Force presentation of forces to a CCDR for the employment of Air Power. Each CCDR is supported by a standing Component Numbered Air Force (C-NAF) to provide planning and execution of aerospace forces in support of CCDR requirements. Each C-NAF consists of a Commander, Air Force Forces (COMAFFOR) and AFFOR/A-staff, and an Air Operations Center (AOC). As needed to support multiple Joint Force Commanders (JFC) in the COCOM's Area of Responsibility (AOR), the C-NAF may deploy Air Component Coordinate Elements (ACCE) to liaise with the JFC. If the Air Force possesses the preponderance of air forces in a JFC's area of operations, the COMAFFOR will also serve as the Joint Forces Air Component Commander (JFACC).

Question: What are "Chopped" units called in the USAF?


Answer: Air and Space Expeditionary Task Force

Question: What is the top level structure of these Chopped forces in the USAF?


Answer: planning and execution of aerospace forces

Question: What does the C-NAF provide support to?


Answer: JFC

Question: Who does the C-NAFF coordinate with on ACEE missions?


Answer: judge advocate general

Context: AFSCs range from officer specialties such as pilot, combat systems officer, missile launch officer, intelligence officer, aircraft maintenance officer, judge advocate general (JAG), medical doctor, nurse or other fields, to various enlisted specialties. The latter range from flight combat operations such as a gunner, to working in a dining facility to ensure that members are properly fed. There are additional occupational fields such as computer specialties, mechanic specialties, enlisted aircrew, communication systems, cyberspace operations, avionics technicians, medical specialties, civil engineering, public affairs, hospitality, law, drug counseling, mail operations, security forces, and search and rescue specialties.

Question: What kind of AFSC is a JAG?


Answer: missile launch officer

Question: What is one of the many types of AFSC employed by the USAF?


Answer: computer specialties

Question: What is an example of an occupational field position in the USAF?


Answer: Explosive Ordnance Disposal

Context: Beyond combat flight crew personnel, perhaps the most dangerous USAF jobs are Explosive Ordnance Disposal (EOD), Combat rescue officer, Pararescue, Security Forces, Combat Control, Combat Weather, Tactical Air Control Party, and AFOSI agents, who deploy with infantry and special operations units who disarm bombs, rescue downed or isolated personnel, call in air strikes and set up landing zones in forward locations. Most of these are enlisted positions augmented by a smaller number of commissioned officers. Other career fields that have seen increasing exposure to combat include civil engineers, vehicle operators, and Air Force Office of Special Investigations (AFOSI) personnel.

Question: What does the abbreviation EOD stand for in the USAF?


Answer: Tactical Air Control Party

Question: What is one of the most dangerous jobs for USAF personnel?


Answer: rescue downed or isolated personnel

Question: What do some of these special missions in the USAF who deploy with the infantry do?


Answer: commissioned officers

Question: What are these enlisted positions in the USAF complimented by?


Answer: Air Force Office of Special Investigations

Question: What other career fields have seen an increase in active combat missions?


Answer: one year of training with a preliminary school

Context: Training programs vary in length; for example, 3M0X1 (Services) has 31 days of tech school training, while 3E8X1 (Explosive Ordnance Disposal) is one year of training with a preliminary school and a main school consisting of over 10 separate divisions, sometimes taking students close to two years to complete. Officer technical training conducted by Second Air Force can also vary by AFSC, while flight training for aeronautically-rated officers conducted by AETC's Nineteenth Air Force can last well in excess of one year.

Question: How long is the training for Explosive Ordnance Disposal in the USAF?


Answer: 3M0X1 (Services)

Question: What USAF tech school has 31 days of training?


Answer: Second Air Force

Question: Who conducts the training for Technical Officers in the USAF?


Answer: excess of one year

Question: How long does the flight training for the AETC's Nineteenth Air Force last?


Answer: enlisted airmen, non-commissioned officers, and commissioned officers

Context: USAF rank is divided between enlisted airmen, non-commissioned officers, and commissioned officers, and ranges from the enlisted Airman Basic (E-1) to the commissioned officer rank of General (O-10). Enlisted promotions are granted based on a combination of test scores, years of experience, and selection board approval while officer promotions are based on time-in-grade and a promotion selection board. Promotions among enlisted personnel and non-commissioned officers are generally designated by increasing numbers of insignia chevrons. Commissioned officer rank is designated by bars, oak leaves, a silver eagle, and anywhere from one to four stars (one to five stars in war-time).[citation needed]

Question: What groups is the USAF rank divided amoung?


Answer: based on a combination of test scores, years of experience, and selection board approval

Question: How are Enlisted promotions in the USAF decided?


Answer: based on time-in-grade and a promotion selection board

Question: How are Officer promotions within the USAF decided?


Answer: designated by bars, oak leaves, a silver eagle, and anywhere from one to four stars

Question: How is a Commissioned Officer's rank shown?


Answer: Reserve Officer Personnel Management Act

Context: Air Force officer promotions are governed by the Defense Officer Personnel Management Act of 1980 and its companion Reserve Officer Personnel Management Act (ROPMA) for officers in the Air Force Reserve and the Air National Guard. DOPMA also establishes limits on the number of officers that can serve at any given time in the Air Force. Currently, promotion from second lieutenant to first lieutenant is virtually guaranteed after two years of satisfactory service. The promotion from first lieutenant to captain is competitive after successfully completing another two years of service, with a selection rate varying between 99% and 100%. Promotion to major through major general is through a formal selection board process, while promotions to lieutenant general and general are contingent upon nomination to specific general officer positions and subject to U.S. Senate approval.

Question: Was does ROPMA stand for in the USAF?


Answer: Defense Officer Personnel Management Act of 1980

Question: What are Air Force Officer promotions overseen by?


Answer: virtually guaranteed after two years

Question: How long does it usually take to be promoted from second to first lieutenant in the USAF?


Answer: DOPMA

Question: Who establishes limits on the amount of Air Force officers?


Answer: Promotion to major through major general

Question: What promotion in the USAF is governed by a formal selection process?


Answer: Air Force Personnel Center at Randolph Air Force Base

Context: During the board process an officer's record is reviewed by a selection board at the Air Force Personnel Center at Randolph Air Force Base in San Antonio, Texas. At the 10 to 11 year mark, captains will take part in a selection board to major. If not selected, they will meet a follow-on board to determine if they will be allowed to remain in the Air Force. Promotion from major to lieutenant colonel is similar and occurs approximately between the thirteen year (for officers who were promoted to major early "below the zone") and the fifteen year mark, where a certain percentage of majors will be selected below zone (i.e., "early"), in zone (i.e., "on time") or above zone (i.e., "late") for promotion to lieutenant colonel. This process will repeat at the 16 year mark (for officers previously promoted early to major and lieutenant colonel) to the 21 year mark for promotion to full colonel.

Question: Where is an officer's record in the USAF reviewed for a promotion?


Answer: Texas

Question: What state is the Randolph Air Force Base located in?


Answer: thirteen year

Question: When does promotion from major to lieutenant colonel in the USAF typically occur?


Answer: 16 year mark

Question: The promotion process repeats when for officers promoted early in the USAF?


Answer: Title 10

Context: Although provision is made in Title 10 of the United States Code for the Secretary of the Air Force to appoint warrant officers, the Air Force does not currently use warrant officer grades, and is the only one of the U.S. Armed Services not to do so. The Air Force inherited warrant officer ranks from the Army at its inception in 1947, but their place in the Air Force structure was never made clear.[citation needed] When the Congress authorized the creation of two new senior enlisted ranks in 1958, Air Force officials privately concluded that these two new "super grades" could fill all Air Force needs then performed at the warrant officer level, although this was not publicly acknowledged until years later.[citation needed] The Air Force stopped appointing warrant officers in 1959, the same year the first promotions were made to the new top enlisted grade, Chief Master Sergeant. Most of the existing Air Force warrant officers entered the commissioned officer ranks during the 1960s, but small numbers continued to exist in the warrant officer grades for the next 21 years.

Question: What section in the US Code for the Secretary of the Air Force allows for the appointment of warrant officers?


Answer: 1947

Question: When did the USAF inherit warrant officer ranks from the Army?


Answer: 1958

Question: When did Congress authorize the creation of two new senior officer grades?


Answer: 1959

Question: When did the USAF stop appointing warrant officers?


Answer: Chief Master Sergeant

Question: What is the newest top enlisted grade in the USAF?


Answer: E-1 (entry level)

Context: Enlisted members of the USAF have pay grades from E-1 (entry level) to E-9 (senior enlisted). While all USAF military personnel are referred to as Airmen, the term also refers to the pay grades of E-1 through E-4, which are below the level of non-commissioned officers (NCOs). Above the pay grade of E-4 (i.e., pay grades E-5 through E-9) all ranks fall into the category of NCO and are further subdivided into "NCOs" (pay grades E-5 and E-6) and "Senior NCOs" (pay grades E-7 through E-9); the term "Junior NCO" is sometimes used to refer to staff sergeants and technical sergeants (pay grades E-5 and E-6).

Question: What is the lowest pay grade in the USAF?


Answer: E-9 (senior enlisted)

Question: What is the highest pay grade in the USAF?


Answer: pay grades E-7 through E-9

Question: What pay grades are included in the USAF for Senior NCOs?


Answer: staff sergeants and technical sergeants

Question: What does junior NCO refer to in the USAF pay grade system?


Answer: pay grade of E-4

Context: The USAF is the only branch of the U.S. military where NCO status is achieved when an enlisted person reaches the pay grade of E-5. In all other branches, NCO status is generally achieved at the pay grade of E-4 (e.g., a Corporal in the Army and Marine Corps, Petty Officer Third Class in the Navy and Coast Guard). The Air Force mirrored the Army from 1976 to 1991 with an E-4 being either a Senior Airman wearing three stripes without a star or a Sergeant (referred to as "Buck Sergeant"), which was noted by the presence of the central star and considered an NCO. Despite not being an NCO, a Senior Airman who has completed Airman Leadership School can be a supervisor according to the AFI 36-2618.

Question: When does NCO status happen in all other branches of the US Military?


Answer: when an enlisted person reaches the pay grade of E-5

Question: When does NCO status occur in the USAF?


Answer: completed Airman Leadership School

Question: What must a Senior Airman do to become a supervisor in the USAF?


Answer: Corporal

Question: What rank is NCO status achieved in the US Army?


Answer: former Bachman-Uxbridge Worsted Company

Context: The first USAF dress uniform, in 1947, was dubbed and patented "Uxbridge Blue" after "Uxbridge 1683 Blue", developed at the former Bachman-Uxbridge Worsted Company. The current Service Dress Uniform, which was adopted in 1993 and standardized in 1995, consists of a three-button, pocketless coat, similar to that of a men's "sport jacket" (with silver "U.S." pins on the lapels, with a silver ring surrounding on those of enlisted members), matching trousers, and either a service cap or flight cap, all in Shade 1620, "Air Force Blue" (a darker purplish-blue). This is worn with a light blue shirt (Shade 1550) and Shade 1620 herringbone patterned necktie. Enlisted members wear sleeve insignia on both the jacket and shirt, while officers wear metal rank insignia pinned onto the coat, and Air Force Blue slide-on epaulet loops on the shirt. USAF personnel assigned to Base Honor Guard duties wear, for certain occasions, a modified version of the standard service dress uniform, but with silver trim on the sleeves and trousers, with the addition of a ceremonial belt (if necessary), wheel cap with silver trim and Hap Arnold Device, and a silver aiguillette placed on the left shoulder seam and all devices and accoutrement.

Question: Where was the Uxbridge Blue dress uniform developed?


Answer: 1947

Question: When was the first USAF dress uniform introduced?


Answer: 1995

Question: When was the current USAF dress uniform standardized?


Answer: pinned onto the coat

Question: Where does an officer in the USAF wear their rank insignia?


Answer: various badges

Context: In addition to basic uniform clothing, various badges are used by the USAF to indicate a billet assignment or qualification-level for a given assignment. Badges can also be used as merit-based or service-based awards. Over time, various badges have been discontinued and are no longer distributed. Authorized badges include the Shields of USAF Fire Protection, and Security Forces, and the Missile Badge (or "pocket rocket"), which is earned after working in a missile system maintenance or missile operations capacity for at least one year.

Question: What is worn by USAF members to indicate a billet assignment?


Answer: merit-based or service-based awards

Question: What else can Badges be used to designate in the USAF?


Answer: Shields of USAF Fire Protection

Question: What is one of the types of Authorized Badges in the USAF?


Answer: at least one year

Question: When is the special "pocket rocket" badge given to USAF personnel working in a missile system operation?


Answer: United States Air Force Academy

Context: Officers may be commissioned upon graduation from the United States Air Force Academy, upon graduation from another college or university through the Air Force Reserve Officer Training Corps (AFROTC) program, or through the Air Force Officer Training School (OTS). OTS, previously located at Lackland AFB, Texas until 1993 and located at Maxwell Air Force Base in Montgomery, Alabama since 1993, in turn encompasses two separate commissioning programs: Basic Officer Training (BOT), which is for line-officer candidates of the active-duty Air Force and the U.S. Air Force Reserve; and the Academy of Military Science (AMS), which is for line-officer candidates of the Air National Guard. (The term "line officer" derives from the concept of the line of battle and refers to an officer whose role falls somewhere within the "Line of the Air", meaning combat or combat-support operations within the scope of legitimate combatants as defined by the Geneva Conventions.)

Question: USAF Officers can be commissioned after graduation from what school?


Answer: Air Force Officer Training School

Question: What is another program that allows officers to become commissioned in the USAF?


Answer: Maxwell Air Force Base in Montgomery, Alabama

Question: Where is the OTS in the US currently located?


Answer: concept of the line of battle and refers to an officer whose role falls somewhere within the "Line of the Air"

Question: What is a line officer in the USAF?


Answer: two

Question: How many commissioning programs does the OTS offer the USAF?


Answer: Commissioned Officer Training

Context: The Air Force also provides Commissioned Officer Training (COT) for officers of all three components who are direct-commissioned to non-line positions due to their credentials in medicine, law, religion, biological sciences, or healthcare administration. Originally viewed as a "knife and fork school" that covered little beyond basic wear of the uniform, COT in recent years has been fully integrated into the OTS program and today encompasses extensive coursework as well as field exercises in leadership, confidence, fitness, and deployed-environment operations.

Question: What does the Air Force provide for officers of direct to non-line positions?


Answer: medicine, law, religion, biological sciences, or healthcare administration

Question: What fields of study in the COT are included in this area of the USAF?


Answer: deployed-environment operations

Question: What is an example of the coursework now offered in the COT in the USAF?


Answer: Fit to Fight program

Context: The US Air Force Fitness Test (AFFT) is designed to test the abdominal circumference, muscular strength/endurance and cardiovascular respiratory fitness of airmen in the USAF. As part of the Fit to Fight program, the USAF adopted a more stringent physical fitness assessment; the new fitness program was put into effect on 1 June 2010. The annual ergo-cycle test which the USAF had used for several years had been replaced in 2004. In the AFFT, Airmen are given a score based on performance consisting of four components: waist circumference, the sit-up, the push-up, and a 1.5-mile (2.4 km) run. Airmen can potentially earn a score of 100, with the run counting as 60%, waist circumference as 20%, and both strength test counting as 10% each. A passing score is 75 points. Effective 1 July 2010, the AFFT is administered by the base Fitness Assessment Cell (FAC), and is required twice a year. Personnel may test once a year if he or she earns a score above a 90%. Additionally, only meeting the minimum standards on each one of these tests will not get you a passing score of 75%, and failing any one component will result in a failure for the entire test.

Question: What is the more strict program that the USAF adopted in 2010 called?


Answer: US Air Force Fitness Test

Question: What test is designed to test the fitness of airmen in the USAF?


Answer: 1.5-mile

Question: How long is the run that the USAF airmen are tested on for the fitness program?


Answer: 75 points

Question: What is a passing score on the US Air Force Fitness Test?


Answer: 90%

Question: What score must an airman get on the US Air Force Fitness test to be able to opt out of one of the mandatory twice a year retests?


Answer: U.S. ground forces

Context: The ground-attack aircraft of the USAF are designed to attack targets on the ground and are often deployed as close air support for, and in proximity to, U.S. ground forces. The proximity to friendly forces require precision strikes from these aircraft that are not possible with bomber aircraft listed below. They are typically deployed as close air support to ground forces, their role is tactical rather than strategic, operating at the front of the battle rather than against targets deeper in the enemy's rear.

Question: What are the ground-attack aircraft in the USAF usually deployed in support for?


Answer: precision strikes

Question: What does the closeness to friendly troops require of these US Air Force aircraft?


Answer: front of the battle

Question: What part of a battle line are the precision strike aircraft of the USAF deployed?


Answer: bomber aircraft

Question: What type of aircraft is not appropriate to be used in close proximity of US ground troops?


Answer: drop bombs

Context: In the US Air Force, the distinction between bombers, fighters that are actually fighter-bombers, and attack aircraft has become blurred. Many attack aircraft, even ones that look like fighters, are optimized to drop bombs, with very little ability to engage in aerial combat. Many fighter aircraft, such as the F-16, are often used as 'bomb trucks', despite being designed for aerial combat. Perhaps the one meaningful distinction at present is the question of range: a bomber is generally a long-range aircraft capable of striking targets deep within enemy territory, whereas fighter bombers and attack aircraft are limited to 'theater' missions in and around the immediate area of battlefield combat. Even that distinction is muddied by the availability of aerial refueling, which greatly increases the potential radius of combat operations. The US, Russia, and the People's Republic of China operate strategic bombers.

Question: What are most attack aircraft in the US Air Force designed to do?


Answer: bomber

Question: What type of USAF aircraft is designed for long range airstrike attacks?


Answer: fighter bombers and attack aircraft

Question: What types of aircraft are typically limited to close proximity of battlefield conflict by the USAF?


Answer: aerial refueling

Question: What increases the radius of combat missions by the US Air Force?


Answer: US, Russia, and the People's Republic of China

Question: What countries utilize strategic bomber aircraft in their missions?


Answer: 1990s

Context: The service's B-2A aircraft entered service in the 1990s, its B-1B aircraft in the 1980s and its current B-52H aircraft in the early 1960s. The B-52 Stratofortress airframe design is over 60 years old and the B-52H aircraft currently in the active inventory were all built between 1960 and 1962. The B-52H is scheduled to remain in service for another 30 years, which would keep the airframe in service for nearly 90 years, an unprecedented length of service for any aircraft. The B-21 is projected to replace the B-52 and parts of the B-1B force by the mid-2020s.

Question: When did the B-2A aircraft enter into service of the US Air Force?


Answer: 1980s

Question: When did the USAF introduce the B-1B aircraft?


Answer: B-52H

Question: What aircraft in the USAF was introduced in the 1960s?


Answer: 30 years

Question: How long is the B-52H scheduled to remain in service of the USAF?


Answer: B-21

Question: What aircraft is scheduled to replace the B-52 in the USAF?


Answer: Cargo and transport

Context: Cargo and transport aircraft are typically used to deliver troops, weapons and other military equipment by a variety of methods to any area of military operations around the world, usually outside of the commercial flight routes in uncontrolled airspace. The workhorses of the USAF Air Mobility Command are the C-130 Hercules, C-17 Globemaster III, and C-5 Galaxy. These aircraft are largely defined in terms of their range capability as strategic airlift (C-5), strategic/tactical (C-17), and tactical (C-130) airlift to reflect the needs of the land forces they most often support. The CV-22 is used by the Air Force for the U.S. Special Operations Command (USSOCOM). It conducts long-range, special operations missions, and is equipped with extra fuel tanks and terrain-following radar. Some aircraft serve specialized transportation roles such as executive/embassy support (C-12), Antarctic Support (LC-130H), and USSOCOM support (C-27J, C-145A, and C-146A). The WC-130H aircraft are former weather reconnaissance aircraft, now reverted to the transport mission.

Question: What type of aircraft is used to deliver troops and weapons to military operations?


Answer: C-130 Hercules, C-17 Globemaster III, and C-5 Galaxy

Question: What aircraft are considered the workhorses of the US Air Force?


Answer: U.S. Special Operations Command

Question: The CV-22 aircraft is used by what section of the USAF?


Answer: LC-130H

Question: What aircraft offers Antarctic Support to the US Air Force?


Answer: weather reconnaissance aircraft

Question: What did the USAF use the WC-130H aircraft for before they converted them for transport missions?


Answer: deny the opponent an advantage in the EMS

Context: The purpose of electronic warfare is to deny the opponent an advantage in the EMS and ensure friendly, unimpeded access to the EM spectrum portion of the information environment. Electronic warfare aircraft are used to keep airspaces friendly, and send critical information to anyone who needs it. They are often called "The Eye in the Sky." The roles of the aircraft vary greatly among the different variants to include Electronic Warfare/Jamming (EC-130H), Psychological Operations/Communications (EC-130J), Airborne Early Warning and Control (E-3), Airborne Command Post (E-4B), ground targeting radar (E-8C), range control (E-9A), and communications relay (E-11A)

Question: What is the purpose of electronic warfare?


Answer: The Eye in the Sky

Question: What nickname is given to Electronic warfare aircraft?


Answer: to keep airspaces friendly, and send critical information to anyone who needs it

Question: What does the USAF use Electronic warfare aircraft for?


Answer: Electronic Warfare/Jamming

Question: What is the EC-130H used for by the US Air Force?


Answer: Airborne Command Post

Question: What does the USAF use the E-4B aircraft for?


Answer: air-to-air combat

Context: The fighter aircraft of the USAF are small, fast, and maneuverable military aircraft primarily used for air-to-air combat. Many of these fighters have secondary ground-attack capabilities, and some are dual-roled as fighter-bombers (e.g., the F-16 Fighting Falcon); the term "fighter" is also sometimes used colloquially for dedicated ground-attack aircraft. Other missions include interception of bombers and other fighters, reconnaissance, and patrol. The F-16 is currently used by the USAF Air Demonstration squadron, the Thunderbirds, while a small number of both man-rated and non-man-rated F-4 Phantom II are retained as QF-4 aircraft for use as Full Scale Aerial Targets (FSAT) or as part of the USAF Heritage Flight program. These extant QF-4 aircraft are being replaced in the FSAT role by early model F-16 aircraft converted to QF-16 configuration. The USAF has 2,025 fighters in service as of September 2012.

Question: What is the primary function of the USAF fighter aircraft?


Answer: F-16 Fighting Falcon

Question: What is the name of a type of dual purpose fighter-bomber aircraft used by the US Air Force?


Answer: F-16

Question: What aircraft is used by the US Air Demonstration group The Thunderbirds?


Answer: F-4 Phantom II

Question: What kind of aircraft is utilized by the USAF in Full Scale Aerial Targets?


Answer: early model F-16 aircraft converted to QF-16 configuration

Question: What are the QF-4 aircraft being replaced by the US Air Force?


Answer: aerial refueling aircraft

Context: The USAF's KC-135 and KC-10 aerial refueling aircraft are based on civilian jets. The USAF aircraft are equipped primarily for providing the fuel via a tail-mounted refueling boom, and can be equipped with "probe and drogue" refueling systems. Air-to-air refueling is extensively used in large-scale operations and also used in normal operations; fighters, bombers, and cargo aircraft rely heavily on the lesser-known "tanker" aircraft. This makes these aircraft an essential part of the Air Force's global mobility and the U.S. force projection. The KC-46A Pegasus is undergoing testing and is projected to be delivered to USAF units starting in 2017.

Question: What kind of aircraft is the USAF's KC-135?


Answer: tail-mounted refueling boom

Question: How does the aerial refueling aircraft supply fuel during flight?


Answer: large-scale operations

Question: When is air-to-air refueling primarily used by the US Air Force?


Answer: KC-46A Pegasus

Question: What aircraft will be available for use by the US Air Force in 2017?


Answer: Robert Gates

Context: In response to the 2007 United States Air Force nuclear weapons incident, Secretary of Defense Robert Gates accepted in June 2009 the resignations of Secretary of the Air Force Michael Wynne and the Chief of Staff of the Air Force General T. Michael Moseley. Moseley's successor, General Norton A. Schwartz, a former tactical airlift and special operations pilot was the first officer appointed to that position who did not have a background as a fighter or bomber pilot. The Washington Post reported in 2010 that General Schwartz began to dismantle the rigid class system of the USAF, particularly in the officer corps.

Question: What US Secretary of Defense accepted resignations of top US Air Force officials in June of 2009?


Answer: Michael Wynne

Question: What US Secretary of the Air Force resigned following a nuclear weapons problem ?


Answer: General Norton A. Schwartz

Question: Who was appointed to the Chief of Staff of the Air Force following Mosley's resignation?


Answer: The Washington Post

Question: What newspaper reported on Schwartz's dismantlement of the US Air Force's class system?


Answer: Major General Charles J. Dunlap, Jr.

Context: Daniel L. Magruder, Jr defines USAF culture as a combination of the rigorous application of advanced technology, individualism and progressive airpower theory. Major General Charles J. Dunlap, Jr. adds that the U.S. Air Force's culture also includes an egalitarianism bred from officers perceiving themselves as their service's principal "warriors" working with small groups of enlisted airmen either as the service crew or the onboard crew of their aircraft. Air Force officers have never felt they needed the formal social "distance" from their enlisted force that is common in the other U.S. armed services. Although the paradigm is changing, for most of its history, the Air Force, completely unlike its sister services, has been an organization in which mostly its officers fought, not its enlisted force, the latter being primarily a rear echelon support force. When the enlisted force did go into harm's way, such as members of multi-crewed aircraft, the close comradeship of shared risk in tight quarters created traditions that shaped a somewhat different kind of officer/enlisted relationship than exists elsewhere in the military.

Question: What author wrote about the US Air Force egalitarian culture?


Answer: an organization in which mostly its officers fought

Question: How does the US Air Force differ from other branches of the military?


Answer: primarily a rear echelon support force

Question: How have the enlisted forces of the US Air Force been seen?


Answer: Cultural and career issues

Context: Cultural and career issues in the U.S. Air Force have been cited as one of the reasons for the shortfall in needed UAV operators. In spite of an urgent need for UAVs or drones to provide round the clock coverage for American troops during the Iraq War, the USAF did not establish a new career field for piloting them until the last year of that war and in 2014 changed its RPA training syllabus again, in the face of large aircraft losses in training, and in response to a GAO report critical of handling of drone programs. Paul Scharre has reported that the cultural divide between the USAF and US Army has kept both services from adopting each other's drone handing innovations.

Question: What is the reason for the shortage of UAV operators in the US Air Force?


Answer: Iraq War

Question: During what war the the USAF establish a new career field for piloting UAVs and drones?


Answer: large aircraft losses in training

Question: Why did the USAF change its training methods on UAVs in 2014?


Answer: US Army

Question: What branch of the US Military does a cultural divide prevent the US Air Force from adopting their drone protocols?


Answer: Royal Air Force

Context: Many of the U.S. Air Force's formal and informal traditions are an amalgamation of those taken from the Royal Air Force (e.g., dining-ins/mess nights) or the experiences of its predecessor organizations such as the U.S. Army Air Service, U.S. Army Air Corps and the U.S. Army Air Forces. Some of these traditions range from "Friday Name Tags" in flying units to an annual "Mustache Month." The use of "challenge coins" is a recent innovation that was adopted from the U.S. Army while another cultural tradition unique to the Air Force is the "roof stomp", practiced by Air Force members to welcome a new commander or to commemorate another event, such as a retirement.

Question: Where did some of the US Air Force traditions come from?


Answer: "Friday Name Tags" in flying units

Question: What traditions does the US Air Force have?


Answer: U.S. Army

Question: What organization did the US Air Force adopt "Challenge Coins" from?


Answer: welcome a new commander or to commemorate another event, such as a retirement

Question: What does the roof stomp tradition signify in the US Air Force?


Answer: "No One Comes Close"

Context: The United States Air Force has had numerous recruiting slogans including "No One Comes Close" and Uno Ab Alto ("One From On High"). For many years, the U.S. Air Force used "Aim High" as its recruiting slogan; more recently, they have used "Cross into the Blue", "We've been waiting for you" and "Do Something Amazing", "Above All", and the newest one, as of 7 October 2010, considered a call and response, "Aim high" followed with the response, "Fly-Fight-Win" Each wing, group, or squadron usually has its own slogan(s). Information and logos can usually be found on the wing, group, or squadron websites.

Question: What was a recent US Air Force recruiting slogan?


Answer: "One From On High"

Question: What does the USAF slogan Uno Ab Alto mean?


Answer: "Aim high" followed with the response, "Fly-Fight-Win"

Question: What is the most recent US Air Force recruitment slogan in October 2010?


Answer: wing, group, or squadron websites

Question: Where can individual each USAF wing, group or squadrons individual motto be found?


Answer: environmental

Context: Recent developments in LEDs permit them to be used in environmental and task lighting. LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. Light-emitting diodes are now used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes and lighted wallpaper. As of 2015[update], LEDs powerful enough for room lighting remain somewhat more expensive, and require more precise current and heat management, than compact fluorescent lamp sources of comparable output.

Question: What type of atmosphere can LED lighting be used?


Answer: longer lifetime

Question: What is an advantage to using LED lighting over the normal light sources?


Answer: Light-emitting diodes

Question: What does LED stand for?


Answer: more expensive

Question: Why are some people hesitant to use LED lighting?


Answer: traffic signals

Question: What is a popular use for LED lighting?


Answer: British

Context: Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide and a cat's-whisker detector. Soviet inventor Oleg Losev reported creation of the first LED in 1927. His research was distributed in Soviet, German and British scientific journals, but no practical use was made of the discovery for several decades. Kurt Lehovec, Carl Accardo and Edward Jamgochian, explained these first light-emitting diodes in 1951 using an apparatus employing SiC crystals with a current source of battery or pulse generator and with a comparison to a variant, pure, crystal in 1953.

Question: What was the nationality of the man who discovered Electroluminescence?


Answer: Electroluminescence

Question: LED lighting is the end result of what phenomenon?


Answer: 1907

Question: When was Electroluminescence discovered?


Answer: Oleg Losev

Question: Who is the Soviet man that created the first LED?


Answer: cat's-whisker

Question: What type of detector did H.J. Round use to help him in his discovery?


Answer: 1957

Context: In 1957, Braunstein further demonstrated that the rudimentary devices could be used for non-radio communication across a short distance. As noted by Kroemer Braunstein".. had set up a simple optical communications link: Music emerging from a record player was used via suitable electronics to modulate the forward current of a GaAs diode. The emitted light was detected by a PbS diode some distance away. This signal was fed into an audio amplifier, and played back by a loudspeaker. Intercepting the beam stopped the music. We had a great deal of fun playing with this setup." This setup presaged the use of LEDs for optical communication applications.

Question: What year was it discovered that early LED instruments could be used for non-radio communication?


Answer: Kroemer Braunstein

Question: Who discovered non-radio uses for early LED devices?


Answer: a GaAs diode

Question: The current in non-radio communication had to go through what type of component?


Answer: a PbS diode

Question: What other component was needed to detect the first current of a non-radio signal?


Answer: audio amplifier

Question: What final device was needed to hear the signal from the initial GaAs diode?


Answer: Texas

Context: In September 1961, while working at Texas Instruments in Dallas, Texas, James R. Biard and Gary Pittman discovered near-infrared (900 nm) light emission from a tunnel diode they had constructed on a GaAs substrate. By October 1961, they had demonstrated efficient light emission and signal coupling between a GaAs p-n junction light emitter and an electrically-isolated semiconductor photodetector. On August 8, 1962, Biard and Pittman filed a patent titled "Semiconductor Radiant Diode" based on their findings, which described a zinc diffused p–n junction LED with a spaced cathode contact to allow for efficient emission of infrared light under forward bias. After establishing the priority of their work based on engineering notebooks predating submissions from G.E. Labs, RCA Research Labs, IBM Research Labs, Bell Labs, and Lincoln Lab at MIT, the U.S. patent office issued the two inventors the patent for the GaAs infrared (IR) light-emitting diode (U.S. Patent US3293513), the first practical LED. Immediately after filing the patent, Texas Instruments (TI) began a project to manufacture infrared diodes. In October 1962, TI announced the first LED commercial product (the SNX-100), which employed a pure GaAs crystal to emit a 890 nm light output. In October 1963, TI announced the first commercial hemispherical LED, the SNX-110.

Question: In what state what near-infrared light emission discovered?


Answer: tunnel

Question: What type of diode was used to help discover near-infrared light emission?


Answer: 1962

Question: In what year was the patent filed for the Semiconductor Radiant Diode?


Answer: GaAs infrared (IR) light-emitting diode

Question: What was the first practical LED?


Answer: Texas Instruments (TI)

Question: The two inventors of the first practical diode were employed by what famous company?


Answer: General Electric Company

Context: The first visible-spectrum (red) LED was developed in 1962 by Nick Holonyak, Jr., while working at General Electric Company. Holonyak first reported his LED in the journal Applied Physics Letters on the December 1, 1962. M. George Craford, a former graduate student of Holonyak, invented the first yellow LED and improved the brightness of red and red-orange LEDs by a factor of ten in 1972. In 1976, T. P. Pearsall created the first high-brightness, high-efficiency LEDs for optical fiber telecommunications by inventing new semiconductor materials specifically adapted to optical fiber transmission wavelengths.

Question: At what global company was the first visible-spectrum LED developed?


Answer: Nick Holonyak, Jr.

Question: What GE employee developed the visible-spectrum LED?


Answer: red

Question: What color is associated with the visible-spectrum LED?


Answer: yellow

Question: What color LED was later created in 1972?


Answer: M. George Craford

Question: What graduate student of Holonyak created the yellow LED?


Answer: replacements for incandescent and neon indicator lamps

Context: The first commercial LEDs were commonly used as replacements for incandescent and neon indicator lamps, and in seven-segment displays, first in expensive equipment such as laboratory and electronics test equipment, then later in such appliances as TVs, radios, telephones, calculators, as well as watches (see list of signal uses). Until 1968, visible and infrared LEDs were extremely costly, in the order of US$200 per unit, and so had little practical use. The Monsanto Company was the first organization to mass-produce visible LEDs, using gallium arsenide phosphide (GaAsP) in 1968 to produce red LEDs suitable for indicators. Hewlett Packard (HP) introduced LEDs in 1968, initially using GaAsP supplied by Monsanto. These red LEDs were bright enough only for use as indicators, as the light output was not enough to illuminate an area. Readouts in calculators were so small that plastic lenses were built over each digit to make them legible. Later, other colors became widely available and appeared in appliances and equipment. In the 1970s commercially successful LED devices at less than five cents each were produced by Fairchild Optoelectronics. These devices employed compound semiconductor chips fabricated with the planar process invented by Dr. Jean Hoerni at Fairchild Semiconductor. The combination of planar processing for chip fabrication and innovative packaging methods enabled the team at Fairchild led by optoelectronics pioneer Thomas Brandt to achieve the needed cost reductions. These methods continue to be used by LED producers.

Question: What was the first commercial uses of LEDs?


Answer: US$200 per unit

Question: How much did the early LEDs cost?


Answer: calculators

Question: What was one use of early LED light in products?


Answer: Hewlett Packard (HP)

Question: What modern company introduced LEDs in 1968?


Answer: 1970s

Question: In what decade were production costs greatly reduced for LEDs to enable successful commercial uses?


Answer: blue

Context: The first high-brightness blue LED was demonstrated by Shuji Nakamura of Nichia Corporation in 1994 and was based on InGaN. In parallel, Isamu Akasaki and Hiroshi Amano in Nagoya were working on developing the important GaN nucleation on sapphire substrates and the demonstration of p-type doping of GaN. Nakamura, Akasaki and Amano were awarded the 2014 Nobel prize in physics for their work. In 1995, Alberto Barbieri at the Cardiff University Laboratory (GB) investigated the efficiency and reliability of high-brightness LEDs and demonstrated a "transparent contact" LED using indium tin oxide (ITO) on (AlGaInP/GaAs).

Question: What color LED was demonstrated in 1994?


Answer: Shuji Nakamura

Question: Who demonstrated the first blue LED?


Answer: 2014 Nobel prize in physics

Question: What did Nakamura, Akasaki, and Amano receive for their work?


Answer: Alberto Barbieri

Question: Who investigated the efficiency of high-brightness LED at Cardiff University in 1995?


Answer: indium tin oxide

Question: What substance did Barbieri use in his work with high-brightness LED?


Answer: white

Context: The attainment of high efficiency in blue LEDs was quickly followed by the development of the first white LED. In this device a Y 3Al 5O 12:Ce (known as "YAG") phosphor coating on the emitter absorbs some of the blue emission and produces yellow light through fluorescence. The combination of that yellow with remaining blue light appears white to the eye. However using different phosphors (fluorescent materials) it also became possible to instead produce green and red light through fluorescence. The resulting mixture of red, green and blue is not only perceived by humans as white light but is superior for illumination in terms of color rendering, whereas one cannot appreciate the color of red or green objects illuminated only by the yellow (and remaining blue) wavelengths from the YAG phosphor.

Question: What LED quickly followed the blue LEDs?


Answer: yellow light

Question: What does the YAG phosphor coating produce?


Answer: P-N junction

Context: A P-N junction can convert absorbed light energy into a proportional electric current. The same process is reversed here (i.e. the P-N junction emits light when electrical energy is applied to it). This phenomenon is generally called electroluminescence, which can be defined as the emission of light from a semi-conductor under the influence of an electric field. The charge carriers recombine in a forward-biased P-N junction as the electrons cross from the N-region and recombine with the holes existing in the P-region. Free electrons are in the conduction band of energy levels, while holes are in the valence energy band. Thus the energy level of the holes will be lesser than the energy levels of the electrons. Some portion of the energy must be dissipated in order to recombine the electrons and the holes. This energy is emitted in the form of heat and light.

Question: What converts absorbed light energy into an electric current?


Answer: electroluminescence

Question: What is the phenomenon where a P-N junction emits light when an electrical current is applied to it?


Answer: the conduction band

Question: Where are the free electrons located in the production of electroluminescence?


Answer: holes existing in the P-region

Question: Whose energy levels are lower than the electrons in the electroluminescence process?


Answer: to recombine the electrons and the holes

Question: Why is some energy in the electroluminescence process emitted as heat and light?


Answer: 2003

Context: In September 2003, a new type of blue LED was demonstrated by Cree that consumes 24 mW at 20 milliamperes (mA). This produced a commercially packaged white light giving 65 lm/W at 20 mA, becoming the brightest white LED commercially available at the time, and more than four times as efficient as standard incandescents. In 2006, they demonstrated a prototype with a record white LED luminous efficacy of 131 lm/W at 20 mA. Nichia Corporation has developed a white LED with luminous efficacy of 150 lm/W at a forward current of 20 mA. Cree's XLamp XM-L LEDs, commercially available in 2011, produce 100 lm/W at their full power of 10 W, and up to 160 lm/W at around 2 W input power. In 2012, Cree announced a white LED giving 254 lm/W, and 303 lm/W in March 2014. Practical general lighting needs high-power LEDs, of one watt or more. Typical operating currents for such devices begin at 350 mA.

Question: In what year was a new type of blue LED produced?


Answer: Cree

Question: Who demonstrated in 2003 the new type of blue LED?


Answer: four times

Question: How much more efficient as standard incandescents was the white LED commercially available in 2003?


Answer: 350 mA

Question: What is the typical operating current for high-power LEDs?


Answer: loss of efficiency

Context: The most common symptom of LED (and diode laser) failure is the gradual lowering of light output and loss of efficiency. Sudden failures, although rare, can also occur. Early red LEDs were notable for their short service life. With the development of high-power LEDs the devices are subjected to higher junction temperatures and higher current densities than traditional devices. This causes stress on the material and may cause early light-output degradation. To quantitatively classify useful lifetime in a standardized manner it has been suggested to use L70 or L50, which are the runtimes (typically given in thousands of hours) at which a given LED reaches 70% and 50% of initial light output, respectively.

Question: What is a symptom of LED failure?


Answer: Sudden failures

Question: What is rare in LED lighting?


Answer: their short service life

Question: What was notable in early red LEDs?


Answer: higher junction temperatures

Question: What could cause early light-output degradation in LEDs?


Answer: L70 or L50

Question: What is a classification used in LED lighting to describe how much usefulness it will receive?


Answer: operating temperature

Context: Since LED efficacy is inversely proportional to operating temperature, LED technology is well suited for supermarket freezer lighting. Because LEDs produce less waste heat than incandescent lamps, their use in freezers can save on refrigeration costs as well. However, they may be more susceptible to frost and snow buildup than incandescent lamps, so some LED lighting systems have been designed with an added heating circuit. Additionally, research has developed heat sink technologies that will transfer heat produced within the junction to appropriate areas of the light fixture.

Question: LED efficacy is inversely proportional to what?


Answer: supermarket freezer

Question: Where is LED lighting very well suited?


Answer: incandescent lamps

Question: LEDs produce less waste heat than what other device?


Answer: frost

Question: What is LED lighting more susceptible to than incandescent light?


Answer: Herb Maruska and Wally Rhines

Context: The first blue-violet LED using magnesium-doped gallium nitride was made at Stanford University in 1972 by Herb Maruska and Wally Rhines, doctoral students in materials science and engineering. At the time Maruska was on leave from RCA Laboratories, where he collaborated with Jacques Pankove on related work. In 1971, the year after Maruska left for Stanford, his RCA colleagues Pankove and Ed Miller demonstrated the first blue electroluminescence from zinc-doped gallium nitride, though the subsequent device Pankove and Miller built, the first actual gallium nitride light-emitting diode, emitted green light. In 1974 the U.S. Patent Office awarded Maruska, Rhines and Stanford professor David Stevenson a patent for their work in 1972 (U.S. Patent US3819974 A) and today magnesium-doping of gallium nitride continues to be the basis for all commercial blue LEDs and laser diodes. These devices built in the early 1970s had too little light output to be of practical use and research into gallium nitride devices slowed. In August 1989, Cree introduced the first commercially available blue LED based on the indirect bandgap semiconductor, silicon carbide (SiC). SiC LEDs had very low efficiency, no more than about 0.03%, but did emit in the blue portion of the visible light spectrum.[citation needed]

Question: What students developed the first blue-violet LED?


Answer: Stanford

Question: The first blue-violet LED was developed at what University?


Answer: 1972

Question: When was the first blue-violet LED developed?


Answer: zinc-doped gallium nitride

Question: What substance helped demonstrate the first blue electroluminescence?


Answer: 1980s

Context: In the late 1980s, key breakthroughs in GaN epitaxial growth and p-type doping ushered in the modern era of GaN-based optoelectronic devices. Building upon this foundation, Dr. Moustakas at Boston University patented a method for producing high-brightness blue LEDs using a new two-step process. Two years later, in 1993, high-brightness blue LEDs were demonstrated again by Shuji Nakamura of Nichia Corporation using a gallium nitride growth process similar to Dr. Moustakas's. Both Dr. Moustakas and Mr. Nakamura were issued separate patents, which confused the issue of who was the original inventor (partly because although Dr. Moustakas invented his first, Dr. Nakamura filed first).[citation needed] This new development revolutionized LED lighting, making high-power blue light sources practical, leading to the development of technologies like BlueRay, as well as allowing the bright high resolution screens of modern tablets and phones.[citation needed]

Question: In what decade were breakthroughs made that brought in the modern era of GaN-based optoelectronic devices?


Answer: Shuji Nakamura

Question: Who first patented a method to produce high-brightness blue LEDs?


Answer: Dr. Moustakas

Question: Who first invented a method to produce high-brightness blue LEDs?


Answer: BlueRay

Question: What technology was made possible by high-power blue light sources?


Answer: tablets

Question: What is one modern gadget that benefits from high-power blue LED lighting?


Answer: Physics

Context: Nakamura was awarded the 2006 Millennium Technology Prize for his invention. Nakamura, Hiroshi Amano and Isamu Akasaki were awarded the Nobel Prize in Physics in 2014 for the invention of the blue LED. In 2015, a US court ruled that three companies (i.e. the litigants who had not previously settled out of court) that had licensed Mr. Nakamura's patents for production in the United States had infringed Dr. Moustakas's prior patent, and order them to pay licensing fees of not less than 13 million USD.

Question: What Nobel Prize did Nakamura, Amano, and Akasaki receive in 2014?


Answer: Millennium Technology Prize

Question: What award did Nakamura receive in 2006 for his invention?


Answer: three

Question: How many companies did a judge say infringed on Dr. Moustakas's prior blue light patent in 2015?


Answer: not less than 13 million USD

Question: What was the fine given to the three companies?


Answer: active region consisting of one or more InGaN quantum wells sandwiched between thicker layers of GaN

Context: By the late 1990s, blue LEDs became widely available. They have an active region consisting of one or more InGaN quantum wells sandwiched between thicker layers of GaN, called cladding layers. By varying the relative In/Ga fraction in the InGaN quantum wells, the light emission can in theory be varied from violet to amber. Aluminium gallium nitride (AlGaN) of varying Al/Ga fraction can be used to manufacture the cladding and quantum well layers for ultraviolet LEDs, but these devices have not yet reached the level of efficiency and technological maturity of InGaN/GaN blue/green devices. If un-alloyed GaN is used in this case to form the active quantum well layers, the device will emit near-ultraviolet light with a peak wavelength centred around 365 nm. Green LEDs manufactured from the InGaN/GaN system are far more efficient and brighter than green LEDs produced with non-nitride material systems, but practical devices still exhibit efficiency too low for high-brightness applications.[citation needed]

Question: What are cladding layers?


Answer: By varying the relative In/Ga fraction in the InGaN quantum wells

Question: How can light emission be varied from violet to amber?


Answer: Aluminium gallium nitride

Question: What does AlGaN stand for?


Answer: Green

Question: What LEDs are more efficient when produced from the InGaN/GaN systems than without?


Answer: aluminium

Context: With nitrides containing aluminium, most often AlGaN and AlGaInN, even shorter wavelengths are achievable. Ultraviolet LEDs in a range of wavelengths are becoming available on the market. Near-UV emitters at wavelengths around 375–395 nm are already cheap and often encountered, for example, as black light lamp replacements for inspection of anti-counterfeiting UV watermarks in some documents and paper currencies. Shorter-wavelength diodes, while substantially more expensive, are commercially available for wavelengths down to 240 nm. As the photosensitivity of microorganisms approximately matches the absorption spectrum of DNA, with a peak at about 260 nm, UV LED emitting at 250–270 nm are to be expected in prospective disinfection and sterilization devices. Recent research has shown that commercially available UVA LEDs (365 nm) are already effective disinfection and sterilization devices. UV-C wavelengths were obtained in laboratories using aluminium nitride (210 nm), boron nitride (215 nm) and diamond (235 nm).

Question: What substance does nitrides contain?


Answer: Ultraviolet

Question: What sort of LEDs are becoming more available on the market?


Answer: 375–395 nm

Question: What is the range of wavelengths for cheap UV LEDs?


Answer: 240 nm

Question: Shorter wavelength diodes provide wavelengths as low as what?


Answer: 250–270 nm

Question: What UV wavelengths are found in sterilization devices?


Answer: red, green, and blue

Context: White light can be formed by mixing differently colored lights; the most common method is to use red, green, and blue (RGB). Hence the method is called multi-color white LEDs (sometimes referred to as RGB LEDs). Because these need electronic circuits to control the blending and diffusion of different colors, and because the individual color LEDs typically have slightly different emission patterns (leading to variation of the color depending on direction) even if they are made as a single unit, these are seldom used to produce white lighting. Nonetheless, this method has many applications because of the flexibility of mixing different colors, and in principle, this mechanism also has higher quantum efficiency in producing white light.[citation needed]

Question: What colors are used to form white light?


Answer: multi-color white LEDs

Question: What is the method called that mixes red, green, and blue colors to form white light?


Answer: electronic circuits

Question: What does the multi-color white LED method need to produce the end result?


Answer: RGB LEDs

Question: What is another name to reference the multi-color white LED method?


Answer: luminous efficacy

Context: There are several types of multi-color white LEDs: di-, tri-, and tetrachromatic white LEDs. Several key factors that play among these different methods, include color stability, color rendering capability, and luminous efficacy. Often, higher efficiency will mean lower color rendering, presenting a trade-off between the luminous efficacy and color rendering. For example, the dichromatic white LEDs have the best luminous efficacy (120 lm/W), but the lowest color rendering capability. However, although tetrachromatic white LEDs have excellent color rendering capability, they often have poor luminous efficacy. Trichromatic white LEDs are in between, having both good luminous efficacy (>70 lm/W) and fair color rendering capability.

Question: What is a factor that may be different in the various types of multi-color white LEDs?


Answer: lower color rendering

Question: Higher efficiency in multi-color white LEDs may mean what?


Answer: tetrachromatic

Question: What is one type of multi-color white LED?


Answer: dichromatic white LEDs

Question: What type has the best luminous efficacy?


Answer: >70 lm/W

Question: What luminous efficacy does trichromatic white LEDs have?


Answer: to form light of different colors

Context: Multi-color LEDs offer not merely another means to form white light but a new means to form light of different colors. Most perceivable colors can be formed by mixing different amounts of three primary colors. This allows precise dynamic color control. As more effort is devoted to investigating this method, multi-color LEDs should have profound influence on the fundamental method that we use to produce and control light color. However, before this type of LED can play a role on the market, several technical problems must be solved. These include that this type of LED's emission power decays exponentially with rising temperature, resulting in a substantial change in color stability. Such problems inhibit and may preclude industrial use. Thus, many new package designs aimed at solving this problem have been proposed and their results are now being reproduced by researchers and scientists.

Question: Multi-color LEDs offer what else besides the formation of white light?


Answer: power decays exponentially with rising temperature

Question: What problem must be solved before multi-color LEDs can play a role in the market?


Answer: substantial change in color stability

Question: What problem results when rising temperatures decays power?


Answer: phosphor-converted white LEDs (pcLEDs)

Context: This method involves coating LEDs of one color (mostly blue LEDs made of InGaN) with phosphors of different colors to form white light; the resultant LEDs are called phosphor-based or phosphor-converted white LEDs (pcLEDs). A fraction of the blue light undergoes the Stokes shift being transformed from shorter wavelengths to longer. Depending on the color of the original LED, phosphors of different colors can be employed. If several phosphor layers of distinct colors are applied, the emitted spectrum is broadened, effectively raising the color rendering index (CRI) value of a given LED.

Question: What method involves coating LEDs of one color with phosphors of different colors?


Answer: blue

Question: In pcLEDs method, a fraction of what light is used?


Answer: Stokes

Question: What shift does blue light undergo in the pcLEDs method?


Answer: the color of the original LED

Question: The different colors of phosphors that can be used is based on what?


Answer: If several phosphor layers of distinct colors are applied

Question: What broadens the emitted spectrum in a pcLEDs method?


Answer: the spectral distribution of the resultant light output

Context: Phosphor-based LED efficiency losses are due to the heat loss from the Stokes shift and also other phosphor-related degradation issues. Their luminous efficacies compared to normal LEDs depend on the spectral distribution of the resultant light output and the original wavelength of the LED itself. For example, the luminous efficacy of a typical YAG yellow phosphor based white LED ranges from 3 to 5 times the luminous efficacy of the original blue LED because of the human eye's greater sensitivity to yellow than to blue (as modeled in the luminosity function). Due to the simplicity of manufacturing the phosphor method is still the most popular method for making high-intensity white LEDs. The design and production of a light source or light fixture using a monochrome emitter with phosphor conversion is simpler and cheaper than a complex RGB system, and the majority of high-intensity white LEDs presently on the market are manufactured using phosphor light conversion.

Question: What do phosphor-based LEDs luminous efficacies depend on?


Answer: phosphor method

Question: What is the most popular method for making high-intensity white LEDs?


Answer: heat loss from the Stokes shift

Question: Why is efficiency sometimes lost in phosphor-based LEDs?


Answer: 3 to 5 times the luminous efficacy

Question: What are some of the luminous efficacies of yellow phosphor based white LED compared to blue?


Answer: monochrome

Question: What type of emitter is used in phosphor-based white LED methods?


Answer: more efficient phosphors

Context: Among the challenges being faced to improve the efficiency of LED-based white light sources is the development of more efficient phosphors. As of 2010, the most efficient yellow phosphor is still the YAG phosphor, with less than 10% Stoke shift loss. Losses attributable to internal optical losses due to re-absorption in the LED chip and in the LED packaging itself account typically for another 10% to 30% of efficiency loss. Currently, in the area of phosphor LED development, much effort is being spent on optimizing these devices to higher light output and higher operation temperatures. For instance, the efficiency can be raised by adapting better package design or by using a more suitable type of phosphor. Conformal coating process is frequently used to address the issue of varying phosphor thickness.

Question: What can improve the efficiency of LED-based white light?


Answer: YAG phosphor

Question: What is the most efficient yellow phosphor?


Answer: less than 10%

Question: What is the percentage of stoke shift loss in YAG phosphor?


Answer: higher operation temperatures

Question: What area are scientists looking into regarding phosphor LED development?


Answer: adapting better package design

Question: What is one method that can raise the efficiency of phosphor-based LEDs?


Answer: near-ultraviolet (NUV) LEDs

Context: White LEDs can also be made by coating near-ultraviolet (NUV) LEDs with a mixture of high-efficiency europium-based phosphors that emit red and blue, plus copper and aluminium-doped zinc sulfide (ZnS:Cu, Al) that emits green. This is a method analogous to the way fluorescent lamps work. This method is less efficient than blue LEDs with YAG:Ce phosphor, as the Stokes shift is larger, so more energy is converted to heat, but yields light with better spectral characteristics, which render color better. Due to the higher radiative output of the ultraviolet LEDs than of the blue ones, both methods offer comparable brightness. A concern is that UV light may leak from a malfunctioning light source and cause harm to human eyes or skin.

Question: White LEDs can be made by coating what?


Answer: copper and aluminium-doped zinc sulfide (ZnS:Cu, Al)

Question: What are near-ultraviolet LEDs coated with to create white LED?


Answer: fluorescent lamps

Question: What device also works in a similar way as NUV LEDs?


Answer: blue

Question: The method of coating NUVs less efficient than what other LEDs?


Answer: UV light

Question: What light can harm human eyes or skin?


Answer: wafers composed of gallium-nitride-on-silicon

Context: A new style of wafers composed of gallium-nitride-on-silicon (GaN-on-Si) is being used to produce white LEDs using 200-mm silicon wafers. This avoids the typical costly sapphire substrate in relatively small 100- or 150-mm wafer sizes. The sapphire apparatus must be coupled with a mirror-like collector to reflect light that would otherwise be wasted. It is predicted that by 2020, 40% of all GaN LEDs will be made with GaN-on-Si. Manufacturing large sapphire material is difficult, while large silicon material is cheaper and more abundant. LED companies shifting from using sapphire to silicon should be a minimal investment.

Question: What is being used to produce white LEDs?


Answer: 200-mm

Question: What size are the wafers used to create white LEDs?


Answer: costly sapphire substrate

Question: By using silicon wafers, what is being avoided?


Answer: mirror-like collector

Question: What needs to be used to reflect light that would otherwise be wasted?


Answer: 2020

Question: By what year will% of all GaN LEDs be made with gallium-nitride-on-silicon wafers?


Answer: Quantum dots

Context: Quantum dots (QD) are semiconductor nanocrystals that possess unique optical properties. Their emission color can be tuned from the visible throughout the infrared spectrum. This allows quantum dot LEDs to create almost any color on the CIE diagram. This provides more color options and better color rendering than white LEDs since the emission spectrum is much narrower, characteristic of quantum confined states. There are two types of schemes for QD excitation. One uses photo excitation with a primary light source LED (typically blue or UV LEDs are used). The other is direct electrical excitation first demonstrated by Alivisatos et al.

Question: What nanocrystals possess unique optical properties?


Answer: create almost any color on the CIE diagram

Question: Quantum Dot LEDs can do what special skill?


Answer: better color rendering

Question: The narrowing of the emission spectrum in Quantum Dot LEDs allows them to do what?


Answer: two

Question: How many types of schemes are there in Quantum Dot LED excitation?


Answer: electrical-excitation

Context: The structure of QD-LEDs used for the electrical-excitation scheme is similar to basic design of OLEDs. A layer of quantum dots is sandwiched between layers of electron-transporting and hole-transporting materials. An applied electric field causes electrons and holes to move into the quantum dot layer and recombine forming an exciton that excites a QD. This scheme is commonly studied for quantum dot display. The tunability of emission wavelengths and narrow bandwidth is also beneficial as excitation sources for fluorescence imaging. Fluorescence near-field scanning optical microscopy (NSOM) utilizing an integrated QD-LED has been demonstrated.

Question: What is one scheme of Quantum Dot excitation?


Answer: hole-transporting materials

Question: What is one material used in electrical-excitation?


Answer: electrons and holes

Question: During the electrical-excitation scheme, what moves into the quantum dot layer?


Answer: near-field scanning optical microscopy (NSOM)

Question: A Quantum Dot LED has been used in what?


Answer: over a thousand

Context: High-power LEDs (HP-LEDs) or high-output LEDs (HO-LEDs) can be driven at currents from hundreds of mA to more than an ampere, compared with the tens of mA for other LEDs. Some can emit over a thousand lumens. LED power densities up to 300 W/cm2 have been achieved. Since overheating is destructive, the HP-LEDs must be mounted on a heat sink to allow for heat dissipation. If the heat from a HP-LED is not removed, the device will fail in seconds. One HP-LED can often replace an incandescent bulb in a flashlight, or be set in an array to form a powerful LED lamp.

Question: How many lumens can some high-power LEDs emit?


Answer: 300 W/cm2

Question: Up to how many densities have been achieved with LED power?


Answer: to allow for heat dissipation

Question: Why must High-power LEDs be mounted on a heat sink?


Answer: the device will fail in seconds

Question: What will happen if the heat from a high-power LED is not removed?


Answer: incandescent bulb in a flashlight

Question: What can one high-power LED replace?


Answer: Seoul Semiconductor

Context: LEDs have been developed by Seoul Semiconductor that can operate on AC power without the need for a DC converter. For each half-cycle, part of the LED emits light and part is dark, and this is reversed during the next half-cycle. The efficacy of this type of HP-LED is typically 40 lm/W. A large number of LED elements in series may be able to operate directly from line voltage. In 2009, Seoul Semiconductor released a high DC voltage LED, named as 'Acrich MJT', capable of being driven from AC power with a simple controlling circuit. The low-power dissipation of these LEDs affords them more flexibility than the original AC LED design.

Question: What company has developed LEDs that can operate on AC power?


Answer: 40 lm/W

Question: What is the efficacy of an AC powered HP-LED?


Answer: 2009

Question: When did Seoul Semiconductor release the first high DC voltage LED?


Answer: more flexibility

Question: What is so good about ac powered HP-LEDs?


Answer: Acrich MJT

Question: What did Seoul Semiconductor name their ac powered HP-LED?


Answer: Alphanumeric

Context: Alphanumeric LEDs are available in seven-segment, starburst and dot-matrix format. Seven-segment displays handle all numbers and a limited set of letters. Starburst displays can display all letters. Dot-matrix displays typically use 5x7 pixels per character. Seven-segment LED displays were in widespread use in the 1970s and 1980s, but rising use of liquid crystal displays, with their lower power needs and greater display flexibility, has reduced the popularity of numeric and alphanumeric LED displays.

Question: What type of LEDs are available in seven-segment format?


Answer: dot-matrix

Question: What is another format that Alphanumeric LEDs are available in?


Answer: Starburst

Question: Which alphanumeric LED display can display all letters?


Answer: 5x7

Question: What type of pixels does a dot matrix display use?


Answer: liquid crystal displays

Question: What has reduced the popularity of numeric LED displays?


Answer: contain their own "smart" control electronics

Context: Digital-RGB LEDs are RGB LEDs that contain their own "smart" control electronics. In addition to power and ground, these provide connections for data-in, data-out, and sometimes a clock or strobe signal. These are connected in a daisy chain, with the data in of the first LED sourced by a microprocessor, which can control the brightness and color of each LED independently of the others. They are used where a combination of maximum control and minimum visible electronics are needed such as strings for Christmas and LED matrices. Some even have refresh rates in the kHz range, allowing for basic video applications.

Question: What makes RGB LEDs different?


Answer: in a daisy chain

Question: How are Digital-RGB LED strobe signals connected?


Answer: microprocessor

Question: What object sources the data in of the first LED of a digital rgb LED?


Answer: control the brightness and color of each LED independently of the others

Question: The microprocessor does what in a digital RGB LED?


Answer: Christmas

Question: What is one example of where Digital RGB LED lights are used?


Answer: multiple LED dice

Context: An LED filament consists of multiple LED dice connected in series on a common longitudinal substrate that form a thin rod reminiscent of a traditional incandescent filament. These are being used as a low cost decorative alternative for traditional light bulbs that are being phased out in many countries. The filaments require a rather high voltage to light to nominal brightness, allowing them to work efficiently and simply with mains voltages. Often a simple rectifier and capacitive current limiting are employed to create a low-cost replacement for a traditional light bulb without the complexity of creating a low voltage, high current converter which is required by single die LEDs. Usually they are packaged in a sealed enclosure with a shape similar to lamps they were designed to replace (e.g. a bulb), and filled with inert nitrogen or carbon dioxide gas to remove heat efficiently.

Question: What does an LED filament consist of?


Answer: a low cost decorative alternative for traditional light bulbs

Question: How are LED filaments used?


Answer: high

Question: What type of voltage is needed for LED filaments?


Answer: a simple rectifier

Question: What helps LED filaments remain low cost?


Answer: high current converter

Question: Single die LEDs require what?


Answer: the current is dependent exponentially on the voltage

Context: The current–voltage characteristic of an LED is similar to other diodes, in that the current is dependent exponentially on the voltage (see Shockley diode equation). This means that a small change in voltage can cause a large change in current. If the applied voltage exceeds the LED's forward voltage drop by a small amount, the current rating may be exceeded by a large amount, potentially damaging or destroying the LED. The typical solution is to use constant-current power supplies to keep the current below the LED's maximum current rating. Since most common power sources (batteries, mains) are constant-voltage sources, most LED fixtures must include a power converter, at least a current-limiting resistor. However, the high resistance of three-volt coin cells combined with the high differential resistance of nitride-based LEDs makes it possible to power such an LED from such a coin cell without an external resistor.

Question: How are LEDs similar to other diodes?


Answer: use constant-current power supplies

Question: What is a solution to preventing an LED failure?


Answer: a small change in voltage

Question: What can cause a large change in current in LEDs?


Answer: batteries

Question: What is a constant-voltage source?


Answer: a power converter

Question: What feature do most LED fixtures need to have?


Answer: Class 1 LED product

Context: The vast majority of devices containing LEDs are "safe under all conditions of normal use", and so are classified as "Class 1 LED product"/"LED Klasse 1". At present, only a few LEDs—extremely bright LEDs that also have a tightly focused viewing angle of 8° or less—could, in theory, cause temporary blindness, and so are classified as "Class 2". The opinion of the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) of 2010, on the health issues concerning LEDs, suggested banning public use of lamps which were in the moderate Risk Group 2, especially those with a high blue component in places frequented by children. In general, laser safety regulations—and the "Class 1", "Class 2", etc. system—also apply to LEDs.

Question: How are most LEDs classified?


Answer: safe under all conditions of normal use

Question: What does being a Class 1 LED product mean?


Answer: extremely bright LEDs

Question: What type of LED can possibly cause blindness?


Answer: French

Question: Which government advocated the banning of Class 2 LEDs?


Answer: Class 2

Question: What class are extremely bright LEDs listed as?


Answer: arsenic

Context: While LEDs have the advantage over fluorescent lamps that they do not contain mercury, they may contain other hazardous metals such as lead and arsenic. Regarding the toxicity of LEDs when treated as waste, a study published in 2011 stated: "According to federal standards, LEDs are not hazardous except for low-intensity red LEDs, which leached Pb [lead] at levels exceeding regulatory limits (186 mg/L; regulatory limit: 5). However, according to California regulations, excessive levels of copper (up to 3892 mg/kg; limit: 2500), lead (up to 8103 mg/kg; limit: 1000), nickel (up to 4797 mg/kg; limit: 2000), or silver (up to 721 mg/kg; limit: 500) render all except low-intensity yellow LEDs hazardous."

Question: What dangerous metal can LEDs contain?


Answer: mercury

Question: What substance does fluorescent lamps contain?


Answer: low-intensity red

Question: Which LEDs are considered dangerous by a 2011 study?


Answer: lead

Question: According to a California study, what harmful metal is in most LEDs?


Answer: low-intensity yellow LEDs

Question: What LEDs are considered safer than any other?


Answer: One-color light

Context: One-color light is well suited for traffic lights and signals, exit signs, emergency vehicle lighting, ships' navigation lights or lanterns (chromacity and luminance standards being set under the Convention on the International Regulations for Preventing Collisions at Sea 1972, Annex I and the CIE) and LED-based Christmas lights. In cold climates, LED traffic lights may remain snow-covered. Red or yellow LEDs are used in indicator and alphanumeric displays in environments where night vision must be retained: aircraft cockpits, submarine and ship bridges, astronomy observatories, and in the field, e.g. night time animal watching and military field use.

Question: What type of light is ideal for traffic signals?


Answer: 1972

Question: In what year were luminescence standards set?


Answer: Red or yellow

Question: What color LEDs are used when night vision is important?


Answer: astronomy observatories

Question: What is an example of a night vision needed area?


Answer: exit signs

Question: What is another use for one-color light?


Answer: brake lights for cars

Context: Because of their long life, fast switching times, and their ability to be seen in broad daylight due to their high output and focus, LEDs have been used in brake lights for cars' high-mounted brake lights, trucks, and buses, and in turn signals for some time, but many vehicles now use LEDs for their rear light clusters. The use in brakes improves safety, due to a great reduction in the time needed to light fully, or faster rise time, up to 0.5 second faster[citation needed] than an incandescent bulb. This gives drivers behind more time to react. In a dual intensity circuit (rear markers and brakes) if the LEDs are not pulsed at a fast enough frequency, they can create a phantom array, where ghost images of the LED will appear if the eyes quickly scan across the array. White LED headlamps are starting to be used. Using LEDs has styling advantages because LEDs can form much thinner lights than incandescent lamps with parabolic reflectors.

Question: Because of their high output, LED lights are very useful where?


Answer: their long life

Question: Why are LED lights sought after for various applications?


Answer: 0.5 second

Question: LED brake lights are how many times faster than incandescent ones?


Answer: White

Question: What color LEDs are now starting to be used more?


Answer: thinner

Question: What types of light can LEDs form better than incandescent?


Answer: theaters

Context: Assistive listening devices in many theaters and similar spaces use arrays of infrared LEDs to send sound to listeners' receivers. Light-emitting diodes (as well as semiconductor lasers) are used to send data over many types of fiber optic cable, from digital audio over TOSLINK cables to the very high bandwidth fiber links that form the Internet backbone. For some time, computers were commonly equipped with IrDA interfaces, which allowed them to send and receive data to nearby machines via infrared.

Question: Where are infrared LEDs used in everday life?


Answer: to send sound to listeners' receivers

Question: How are LEDs used in theaters?


Answer: fiber optic

Question: LEDs can send data over what type of cable?


Answer: very high bandwidth

Question: What type of fiber forms the backbone of the internet?


Answer: US

Context: In the US, one kilowatt-hour (3.6 MJ) of electricity currently causes an average 1.34 pounds (610 g) of CO 2 emission. Assuming the average light bulb is on for 10 hours a day, a 40-watt bulb will cause 196 pounds (89 kg) of CO 2 emission per year. The 6-watt LED equivalent will only cause 30 pounds (14 kg) of CO 2 over the same time span. A building’s carbon footprint from lighting can therefore be reduced by 85% by exchanging all incandescent bulbs for new LEDs if a building previously used only incandescent bulbs.

Question: In what country does one kilowatt-hour of electricity causes 1.34 pounds of CO 2 emission?


Answer: 196 pounds

Question: How much CO2 emission would a 40-watt light bulb produce after 10 hours?


Answer: 30 pounds

Question: A 6-watt LED left on for 10 hours a day will emit how much CO 2?


Answer: 85%

Question: How much can a building's carbon footprint be reduced by switching to LEDs?


Answer: Machine vision

Context: Machine vision systems often require bright and homogeneous illumination, so features of interest are easier to process. LEDs are often used for this purpose, and this is likely to remain one of their major uses until the price drops low enough to make signaling and illumination uses more widespread. Barcode scanners are the most common example of machine vision, and many low cost products use red LEDs instead of lasers. Optical computer mice are an example of LEDs in machine vision, as it is used to provide an even light source on the surface for the miniature camera within the mouse. LEDs constitute a nearly ideal light source for machine vision systems for several reasons:

Question: LEDs are often used for what type of systems?


Answer: so features of interest are easier to process

Question: Why are LEDs preferred for machine vision systems?


Answer: price drops

Question: What can help make LEDs more widely used?


Answer: Barcode scanners

Question: What is the most common example of a machine vision system?


Answer: Optical computer mice

Question: Where are some LEDs in machine vision systems found?


Answer: free space optics communications

Context: The light from LEDs can be modulated very quickly so they are used extensively in optical fiber and free space optics communications. This includes remote controls, such as for TVs, VCRs, and LED Computers, where infrared LEDs are often used. Opto-isolators use an LED combined with a photodiode or phototransistor to provide a signal path with electrical isolation between two circuits. This is especially useful in medical equipment where the signals from a low-voltage sensor circuit (usually battery-powered) in contact with a living organism must be electrically isolated from any possible electrical failure in a recording or monitoring device operating at potentially dangerous voltages. An optoisolator also allows information to be transferred between circuits not sharing a common ground potential.

Question: Where are LEDs often used?


Answer: medical equipment

Question: Where are opto-isolators found?


Answer: remote controls

Question: What is an example of a device that uses free space optic communications?


Answer: allows information to be transferred between circuits not sharing a common ground potential

Question: What does an optoisolator do?


Answer: LED Computers

Question: In what common household item can you find infrared LEDs?


Answer: Nintendo Wii

Context: Many sensor systems rely on light as the signal source. LEDs are often ideal as a light source due to the requirements of the sensors. LEDs are used as motion sensors, for example in optical computer mice. The Nintendo Wii's sensor bar uses infrared LEDs. Pulse oximeters use them for measuring oxygen saturation. Some flatbed scanners use arrays of RGB LEDs rather than the typical cold-cathode fluorescent lamp as the light source. Having independent control of three illuminated colors allows the scanner to calibrate itself for more accurate color balance, and there is no need for warm-up. Further, its sensors only need be monochromatic, since at any one time the page being scanned is only lit by one color of light. Since LEDs can also be used as photodiodes, they can be used for both photo emission and detection. This could be used, for example, in a touchscreen that registers reflected light from a finger or stylus. Many materials and biological systems are sensitive to, or dependent on, light. Grow lights use LEDs to increase photosynthesis in plants, and bacteria and viruses can be removed from water and other substances using UV LEDs for sterilization.

Question: What video game console uses infrared LEDs?


Answer: Pulse oximeters

Question: What device uses infrared LEDs to measure oxygen saturation?


Answer: RGB LEDs

Question: Some flatbed scanners use what type of LED?


Answer: warm-up

Question: By using LEDs, scanners do not have to what?


Answer: increase photosynthesis in plants

Question: Grow lights use LEDs for what process?


Answer: medium-quality

Context: LEDs have also been used as a medium-quality voltage reference in electronic circuits. The forward voltage drop (e.g. about 1.7 V for a normal red LED) can be used instead of a Zener diode in low-voltage regulators. Red LEDs have the flattest I/V curve above the knee. Nitride-based LEDs have a fairly steep I/V curve and are useless for this purpose. Although LED forward voltage is far more current-dependent than a Zener diode, Zener diodes with breakdown voltages below 3 V are not widely available.

Question: What quality has LEDs been used as?


Answer: Red

Question: What LED has the flattest I/V curve above the knee?


Answer: Nitride-based LEDs

Question: What LEDs have a very steep I/V curve?


Answer: Zener

Question: LED forward voltage is more current-dependent than what diode?


Answer: 3 V

Question: Zener diodes below what voltage are not widely available?


Answer: Birds

Context: Birds (Aves) are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. They rank as the class of tetrapods with the most living species, at approximately ten thousand, with more than half of these being passerines, sometimes known as perching birds or, less accurately, as songbirds.

Question: What is a group of endothermic vertebrates characterised by feathers and toothless beaked jaws?


Answer: bee hummingbird

Question: What is the smallest bird?


Answer: ostrich

Question: What is the largest bird?


Answer: 5 cm (2 in)

Question: What is the size of the smallest bird?


Answer: 2.75 m (9 ft)

Question: What is the size of the largest bird?


Answer: birds

Context: The fossil record indicates that birds are the last surviving dinosaurs, having evolved from feathered ancestors within the theropod group of saurischian dinosaurs. True birds first appeared during the Cretaceous period, around 100 million years ago. DNA-based evidence finds that birds diversified dramatically around the time of the Cretaceous–Paleogene extinction event that killed off all other dinosaurs. Birds in South America survived this event and then migrated to other parts of the world via multiple land bridges while diversifying during periods of global cooling. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period. Many of these early "stem-birds", such as Archaeopteryx, were not yet capable of fully powered flight, and many retained primitive characteristics like toothy jaws in place of beaks, and long bony tails.

Question: What are the last surviving dinosaurs, according o the fossil record?


Answer: Cretaceous period

Question: When did true birds first appear?


Answer: Archaeopteryx

Question: Name an example of an early stem-bird.


Answer: digestive and respiratory systems

Context: Birds have wings which are more or less developed depending on the species; the only known groups without wings are the extinct moas and elephant birds. Wings, which evolved from forelimbs, give most birds the ability to fly, although further speciation has led to some flightless birds, including ratites, penguins, and diverse endemic island species of birds. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly the aforementioned flightless penguins, and also members of the duck family, have also evolved for swimming. Birds, specifically Darwin's finches, played an important part in the inception of Darwin's theory of evolution by natural selection.

Question: What makes birds uniquely adapted for flight?


Answer: Darwin's finches

Question: What type of bird particularly played an important part in the inception of Darwin's theory of evolution by natural selection?


Answer: Wings

Question: Which part of the bird developed from forelimbs?


Answer: corvids and parrots

Context: Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, and many social species pass on knowledge across generations, which is considered a form of culture. Many species annually migrate great distances. Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have polygynous ("many females") or, rarely, polyandrous ("many males") breeding systems. Birds produce offspring by laying eggs which are fertilized through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilized, though unfertilized eggs do not produce offspring.

Question: Which type of birds are among the most intelligent animals?


Answer: by laying eggs which are fertilized through sexual reproduction

Question: How to birds produce offspring?


Answer: nest

Question: Where are eggs usually laid?


Answer: Songbirds, parrots

Context: Many species of birds are economically important. Domesticated and undomesticated birds (poultry and game) are important sources of eggs, meat, and feathers. Songbirds, parrots, and other species are popular as pets. Guano (bird excrement) is harvested for use as a fertilizer. Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry.

Question: Which birds are popular as pets?


Answer: bird excrement

Question: What is guano?


Answer: Guano

Question: What is the name of bird excrement?


Answer: Guano

Question: What is harvested for use as fertilizer?


Answer: 120–130

Question: How many species of birds have become extinct as a result of human activity?