Question

A star is moving away from an observer at 1% of the speed of light. At what wavelength would the observer find an emission line which would occur at a wavelength of 6000 Angstroms if the star were at rest?
a. 6060 Angstroms
b. 6010 Angstroms
c. 6000 Angstroms
d. 5940 Angstroms

Answer 1

Relative change in frequency = v/c

Where v is the speed that the body moves away at, and c is the speed of light.

Relative change in frequency = - (Relative change in Wavelength)

=> - (Relative change in Wavelength) = v/c
=> -(Change in wavelength/Original Wavelength) = v/c

Plug in your values.

Answer 2

C