Optics Problems - Numerical 32

The spectral line for a given element in the light received from a distant star is shifted towards a longer wavelength by 0.030%. Calculate the velocity of the star in the line of sight.

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Suggested solution:

Suggested solution:

Since l is increasing, the star is receding from the earth. Let v be the speed of the star with respect to the earth: The apparent wavelength 'l' is

where c is the actual wave length.

or v = 9 x 10⁴ m/s