Which phenomena is used to estimate the velocity of star with respect to the earth?

CONCEPT:

Doppler effect of light:

• Doppler shift is also known as the Doppler effect is defined as the change in the wavelength or frequency of the waves with respect to the observer who is in motion relative to the wave source.
• The phenomenon was described in the year 1842 by the Austrian physicist Christian Doppler.
• This phenomenon is used to find the velocity of the star with respect to the earth.
• Doppler's shift is given by,

\(⇒ Δλ=\frac{vλ}{c}\) 

Where, Δλ = doppler shift(Å), v = velocity(m/s), λ = wavelength(Å), and c = speed of light = 3×108 m/s

EXPLANATION:

• Doppler effect is used to find the velocity of the star with respect to the earth.
• Hence, option 3 is correct.