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 4.5–6%. 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: The onset of infrared is defined (according to different standards) at various values typically between 700 nm and 800 nm, but the boundary between visible and infrared light is not precisely defined. The human eye is markedly less sensitive to light above 700 nm wavelength, so longer wavelengths make insignificant contributions to scenes illuminated by common light sources. However, particularly intense near-IR light (e.g., from IR lasers, IR LED sources, or from bright daylight with the visible light removed by colored gels) can be detected up to approximately 780 nm, and will be perceived as red light. Sources providing wavelengths as long as 1050 nm can be seen as a dull red glow in intense sources, causing some difficulty in near-IR illumination of scenes in the dark (usually this practical problem is solved by indirect illumination). Leaves are particularly bright in the near IR, and if all visible light leaks from around an IR-filter are blocked, and the eye is given a moment to adjust to the extremely dim image coming through a visually opaque IR-passing photographic filter, it is possible to see the Wood effect that consists of IR-glowing foliage.
What sort of light is generated by IR lasers?
The answer is the following: near-IR

Problem: Near New Haven there is the static inverter plant of the HVDC Cross Sound Cable. There are three PureCell Model 400 fuel cells placed in the city of New Haven—one at the New Haven Public Schools and newly constructed Roberto Clemente School, one at the mixed-use 360 State Street building, and one at City Hall. According to Giovanni Zinn of the city's Office of Sustainability, each fuel cell may save the city up to $1 million in energy costs over a decade. The fuel cells were provided by ClearEdge Power, formerly UTC Power.
What was the former name of the company that provided the fuel cells to the city?
The answer is the following: UTC Power

Problem: There is controversy around the recognition of the Alsacian flag. The authentic historical flag is the Rot-un-Wiss ; Red and White are commonly found on the coat of arms of Alsacian cities (Strasbourg, Mulhouse, Sélestat...) and of many Swiss cites, especially in Basel's region. The German region Hesse uses a flag similar to the Rot-un-Wiss. As it underlines the Germanic roots of the region, it was replaced in 1949 by a new "Union jack-like" flag representing the union of the two déprtements. It has, however, no real historical relevance. It has been since replaced again by a slightly different one, also representing the two départements. With the purpose of "Frenchizing" the region, the Rot-un-Wiss has not been recognized by Paris. Some overzealous statesmen have called it a Nazi invention - while its origins date back to the XIth century and the Red and White banner of Gérard de Lorraine (aka. d'Alsace). The Rot-un-Wiss flag is still known as the real historical emblem of the region by most of the population and the departments' parliaments and has been widely used during protests against the creation of a new "super-region" gathering Champagne-Ardennes, Lorraine and Alsace, namely on Colmar's statue of liberty.
What is the name of the historical flag of Alsace?
The answer is the following:
Rot-un-Wiss