Problem: Glass:

Most common glass contains other ingredients to change its properties. Lead glass or flint glass is more 'brilliant' because the increased refractive index causes noticeably more specular reflection and increased optical dispersion. Adding barium also increases the refractive index. Thorium oxide gives glass a high refractive index and low dispersion and was formerly used in producing high-quality lenses, but due to its radioactivity has been replaced by lanthanum oxide in modern eyeglasses.[citation needed] Iron can be incorporated into glass to absorb infrared energy, for example in heat absorbing filters for movie projectors, while cerium(IV) oxide can be used for glass that absorbs UV wavelengths.

What is the benefit of heat absorbing filters in addition to its refractive index?
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A: unanswerable


Problem: The rivalries between the Arab tribes had caused unrest in the provinces outside Syria, most notably in the Second Muslim Civil War of 680–692 CE and the Berber Revolt of 740–743 CE. During the Second Civil War, leadership of the Umayyad clan shifted from the Sufyanid branch of the family to the Marwanid branch. As the constant campaigning exhausted the resources and manpower of the state, the Umayyads, weakened by the Third Muslim Civil War of 744–747 CE, were finally toppled by the Abbasid Revolution in 750 CE/132 AH. A branch of the family fled across North Africa to Al-Andalus, where they established the Caliphate of Córdoba, which lasted until 1031 before falling due to the Fitna of al-Ándalus.
When did leadership shift from the Marwanid branch to the Sufyanid branch?
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Answer: unanswerable


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
In the past, people at Eton have occasionally been guilty of antisemitism. For a time, new admissions were called 'Jews' by their fellow Collegers. In 1945, the school introduced a nationality statute conditioning entry on the applicant's father being British by birth. The statute was removed after the intervention of Prime Minister Harold Macmillan in the 1960s after it came to the attention of Oxford's Wykeham Professor of Logic, A. J. Ayer, himself Jewish and an Old Etonian, who "suspected a whiff of anti-semitism".
For what reason as the 1945 entrance stipulation removed?
A: "suspected a whiff of anti-semitism"


Context and question: With the emerging knowledge in scientific fields and the rise of new materials and technology, architecture and engineering began to separate, and the architect began to concentrate on aesthetics and the humanist aspects, often at the expense of technical aspects of building design. There was also the rise of the "gentleman architect" who usually dealt with wealthy clients and concentrated predominantly on visual qualities derived usually from historical prototypes, typified by the many country houses of Great Britain that were created in the Neo Gothic or Scottish Baronial styles. Formal architectural training in the 19th century, for example at École des Beaux-Arts in France, gave much emphasis to the production of beautiful drawings and little to context and feasibility. Effective architects generally received their training in the offices of other architects, graduating to the role from draughtsmen or clerks.
 What did 18th century formal architectural training neglect?
Answer: unanswerable


Question: The newly invented Western Electric moving coil or dynamic microphone was part of the Wide Range System. It had a flatter audio response than the old style Wente condenser type and didn't require electronics installed in the microphone housing. Signals fed to the cutting head were pre-emphasized in the treble region to help override noise in playback. Groove cuts in the vertical plane were employed rather than the usual lateral cuts. The chief advantage claimed was more grooves per inch that could be crowded together, resulting in longer playback time. Additionally, the problem of inner groove distortion, which plagued lateral cuts, could be avoided with the vertical cut system. Wax masters were made by flowing heated wax over a hot metal disc thus avoiding the microscopic irregularities of cast blocks of wax and the necessity of planing and polishing.
Is there an answer to this question: How was the moving coil microphone unique to the Wente type?

Answer: didn't require electronics installed in the microphone housing


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Several solid dielectrics are available, including paper, plastic, glass, mica and ceramic materials. Paper was used extensively in older devices and offers relatively high voltage performance. However, it is susceptible to water absorption, and has been largely replaced by plastic film capacitors. Plastics offer better stability and ageing performance, which makes them useful in timer circuits, although they may be limited to low operating temperatures and frequencies. Ceramic capacitors are generally small, cheap and useful for high frequency applications, although their capacitance varies strongly with voltage and they age poorly. They are broadly categorized as class 1 dielectrics, which have predictable variation of capacitance with temperature or class 2 dielectrics, which can operate at higher voltage. Glass and mica capacitors are extremely reliable, stable and tolerant to high temperatures and voltages, but are too expensive for most mainstream applications. Electrolytic capacitors and supercapacitors are used to store small and larger amounts of energy, respectively, ceramic capacitors are often used in resonators, and parasitic capacitance occurs in circuits wherever the simple conductor-insulator-conductor structure is formed unintentionally by the configuration of the circuit layout.
What sort of circuit are plastic capacitors especially useful for?
A:
timer circuits