Problem: In the last two decades, photovoltaics (PV), also known as solar PV, has evolved from a pure niche market of small scale applications towards becoming a mainstream electricity source. A solar cell is a device that converts light directly into electricity using the photoelectric effect. The first solar cell was constructed by Charles Fritts in the 1880s. In 1931 a German engineer, Dr Bruno Lange, developed a photo cell using silver selenide in place of copper oxide. Although the prototype selenium cells converted less than 1% of incident light into electricity, both Ernst Werner von Siemens and James Clerk Maxwell recognized the importance of this discovery. Following the work of Russell Ohl in the 1940s, researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the crystalline silicon solar cell in 1954. These early solar cells cost 286 USD/watt and reached efficiencies of 4.56%. By 2012 available efficiencies exceed 20% and the maximum efficiency of research photovoltaics is over 40%.
Who created the first solar cell?
The answer is the following: Charles Fritts

Problem: Many other builds were released until the Japan's Developers Day conference, when Steven Sinofsky announced that Windows 8 Release Preview (build 8400) would be released during the first week of June. On May 28, 2012, Windows 8 Release Preview (Standard Simplified Chinese x64 edition, not China-specific version, build 8400) was leaked online on various Chinese and BitTorrent websites. On May 31, 2012, Windows 8 Release Preview was released to the public by Microsoft. Major items in the Release Preview included the addition of Sports, Travel, and News apps, along with an integrated version of Adobe Flash Player in Internet Explorer. Like the Developer Preview and the Consumer Preview, the release preview expired on January 15, 2013.
When was the release preview set to expire?
The answer is the following: January 15, 2013

Problem: By summer 1918, a million American soldiers, or "doughboys" as they were often called, of the American Expeditionary Forces were in Europe under the command of John J. Pershing, with 25,000 more arriving every week. The failure of Germany's spring offensive exhausted its reserves and they were unable to launch new offensives. The German Navy and home front then revolted and a new German government signed a conditional surrender, the Armistice, ending the war against the western front on November 11, 1918.
What was the name of the conditional surrender that ended fighting on the western front?
The answer is the following: the Armistice

Problem: All England matches are broadcast with full commentary on BBC Radio 5 Live. From the 200809 season until the 201718 season, England's home and away qualifiers, and friendlies both home and away are broadcast live on ITV (often with the exception of STV, the ITV affiliate in central and northern Scotland). England's away qualifiers for the 2010 World Cup were shown on Setanta Sports until that company's collapse. As a result of Setanta Sports's demise, England's World Cup qualifier in Ukraine on 10 October 2009 was shown in the United Kingdom on a pay-per-view basis via the internet only. This one-off event was the first time an England game had been screened in such a way. The number of subscribers, paying between 4.99 and 11.99 each, was estimated at between 250,000 and 300,000 and the total number of viewers at around 500,000.
In what year was an England football match aired only via the internet for the first time?
The answer is the following:
2009