Question

if the following line represents unshifted light from a star, which of these shows how light wave would change if the star started moving away from the observer? unshifted light

Explanation:

When a star moves away from an observer, the light it emits undergoes a redshift. This means the wavelength of the light increases. In a wave - diagram, an increased wavelength is represented by a wave that is stretched out (longer between crests or troughs). Option A shows a wave that is stretched compared to the unshifted light (original wave), while Option B shows a wave with a shorter wavelength (blueshift, which would occur if the star were moving towards the observer), Option C is not a wave (a straight line, no wave - like properties), and Option D is a saw - tooth wave which is not a representation of light wave behavior in this context.

Answer:

A.