Question

State whether the light from an object moving towards us will be red shifted or blue shifted and explain why.

Answer 1

Answer:

The light from an object which is coming towards us will be blue shifted.

Explanation:

According to the Doppler effect the movement of the source towards the observer will lead to increase in thew apparent frequency by the Doppler formula,

$f'=\frac{c+v_{o} }{c-v_{s} }f$

Now when the there is increase in frequency then the wavelength is decrease because it is inversely related to frequency.

The wavelength of blue shift is lies in the range of 450-490 nm and the wavelength of red shift lies in the region of 635-700 nm.

Therefore, decrease in the wavelength will lead to blue shift.