Problem: The Scheinergrade (Sch.) system was devised by the German astronomer Julius Scheiner (18581913) in 1894 originally as a method of comparing the speeds of plates used for astronomical photography. Scheiner's system rated the speed of a plate by the least exposure to produce a visible darkening upon development. Speed was expressed in degrees Scheiner, originally ranging from 1 Sch. to 20 Sch., where an increment of 19 Sch. corresponded to a hundredfold increase in sensitivity, which meant that an increment of 3 Sch. came close to a doubling of sensitivity.
Who created the Scheinergrade system?
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Answer: the German astronomer Julius Scheiner

Problem: Luminous efficacy of a light source may be defined in two ways. The radiant luminous efficacy (LER) is the ratio of the visible light flux emitted (the luminous flux) to the total power radiated over all wavelengths. The source luminous efficacy (LES) is the ratio of the visible light flux emitted (the luminous flux) to the total power input to the source, such as a lamp. Visible light is measured in lumens, a unit which is defined in part by the differing sensitivity of the human eye to different wavelengths of light. Not all wavelengths of visible electromagnetic energy are equally effective at stimulating the human eye; the luminous efficacy of radiant energy (LER) is a measure of how well the distribution of energy matches the perception of the eye. The units of luminous efficacy are "lumens per watt" (lpw). The maximum LER possible is 683 lm/W for monochromatic green light at 555 nanometers wavelength, the peak sensitivity of the human eye.
What does the acronym LES refer to?
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Answer: source luminous efficacy

Problem: Some of Jackson's successors made no use of the veto power, while others used it intermittently. It was only after the Civil War that presidents began to use the power to truly counterbalance Congress. Andrew Johnson, a Democrat, vetoed several Reconstruction bills passed by the "Radical Republicans." Congress, however, managed to override fifteen of Johnson's twenty-nine vetoes. Furthermore, it attempted to curb the power of the presidency by passing the Tenure of Office Act. The Act required Senate approval for the dismissal of senior Cabinet officials. When Johnson deliberately violated the Act, which he felt was unconstitutional (Supreme Court decisions later vindicated such a position), the House of Representatives impeached him; he was acquitted in the Senate by one vote.
After which war did Congress begin using power to counterbalance the President?
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Answer:
unanswerable