The stratosphere is heated by
a. warm air rising from the troposphere.
b. ultraviolet light from the Sun.
c. convection.
d. x-rays.
e. all of the above.
Ans: b. ultraviolet light from the Sun.
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A satellite is powered by a small nuclear generator that puts out 10 W. How much matter is converted into energy over the 20-year life span of the generator?
a. 70 µg b. 70 g c. 7 g d. 7 kg e. 4 mg
A capacitor C is connected in series with a resistor R across a battery and an open switch. If a second capacitor of capacitance 2C is connected in series to the first, the time constant of the new RC circuit will be
A) the same as before. B) larger than before. C) smaller than before. D) variable.
Coal is formed from
A) anthracite. B) deeply buried oil sediments. C) swamps. D) lithified peat.
Current: A jeweler needs to electroplate gold, having an atomic mass of 196.97 g/mol, onto a bracelet. He knows that the charge carriers in the ionic solution are singly-ionized gold ions, Au+, and has calculated that he must deposit 0.20 g of gold to reach the necessary thickness. How much current does he need to plate the bracelet in 3.0 hours? (e = 1.60 × 10-19 C, NA = 6.02 × 1023 atoms/mol)
A. 9.1 mA B. 540 mA C. 33 A D. 1800 mA