In the spectrum of light of a luminous heavenly body the wavelength of a spectral line is measured to be $4747\mathring{\mathrm{A}}$ while actual wavelength of the line is $4700\mathring{\mathrm{A}}$. The relative velocity of the heavenly body with respect to earth will be (velocity of light is $3 imes 10^{8}m/s$)

Question

In the spectrum of light of a luminous heavenly body the wavelength of a spectral line is measured to be $4747\mathring{\mathrm{A}}$ while actual wavelength of the line is $4700\mathring{\mathrm{A}}$. The relative velocity of the heavenly body with respect to earth will be (velocity of light is $3 	imes 10^{8}m/s$)

Dr. Abubacker · Accepted Answer

(d) $\Delta\lambda = \frac{v_{s}}{c}\lambda \Rightarrow v_{s} = \frac{\Delta\lambda.c}{\lambda} = \frac{47 	imes 3 	imes 10^{8}}{4700}$
$= 3 	imes 10^{6}m/s$ away from earth

Explanation

Reviewed by Dr. Abubacker

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