Author Question: If a hydrogen emission line appears at 656.2 nm in the laboratory, what can we say about a cloud of ... (Read 180 times)

fagboi · **on:** Jul 27, 2018

If a hydrogen emission line appears at 656.2 nm in the laboratory, what can we say about a cloud of hydrogen gas with this same emission line at 680.2 nm?

A) The location of the emission line has nothing to do with speed.
B) It is neither receding nor approaching us.
C) It is approaching us.
D) It is receding away from us.

Question 2

The Moon is nearly tidally locked to the Earth, which means the Moon's rotation period is almost the same as its orbital period. If you were camped at the equator of the Moon, you would experience (approximately)

A) (14 24 ) hours of darkness followed by (14 24 ) hours of sunshine.
B) 14 hours of darkness followed by 14 hours of sunshine.
C) sunshine all the time, except when the Earth blocks the Sun.
D) sunshine (day) all the time.