Question

Identify the statement that correctly describes light and how it travels? (2 points)

Select one:
a. Light waves can travel in a vacuum and travel at a constant speed even if the light source is moving.
b. Light waves can travel in a vacuum and will travel faster if the light source is moving forward.
c. Light waves need a medium to travel, and they travel faster if the light source is moving forward.
d. Light waves need a medium to travel, and they travel at the same speed even if the light source is moving.

Answer 1

Light does not travel at a constant speed in a vacuum, compared to in air, because the light is being absorbed by atoms and molecules in the air. But light does travel at a constant speed in a vacuum.
So I agree with A
All that talk about moving forward is irrelevant (I think)

Answer 2

A vacuum implies an absence of any material, not just air. Light has a fixed speed in a vacuum of about 300,000km per second. There is no medium for electromagnetic radiation and the speed is unaffected by a moving source. The notion of the ether as a medium for light was found to be false by experiment. Answer a applies.