1. If the Earth-Sun distance were doubled, the intensity of radiation from the Sun that reaches the Earth's surface would
(a) Quadruple.
(b) Double.
(c) Drop to 1/2
(d) Drop to 1/4
2. An electromagnetic wave is traveling straight down toward the center of the Earth. At a certain moment in time the electric field points west. In which direction does the magnetic field point at this moment?
(a) North.
(b) South.
(c) East.
(d) West.
(e) Up.
(f) Down.
(g) Either (a) or (b).
(h) Either (c) or (d).
(i) Either (e) or (f).