Doppler shift for the light of wavelength 6000 Å emitted from the sun is 0.04 Å. If radius of the sun is 7 × 10⁸ m then time period of rotation of the sun will be

25 days

Doppler shift, $d \lambda=\frac{v}{c} × \lambda=R_{ϖ}\left(\frac{\lambda}{c}\right)$

or $R\left(\frac{2 \pi}{T}\right) \frac{\lambda}{c}=d \lambda$

Substituting values for all parameter, we get

or $T=\frac{R \times 2 \pi}{d \lambda} \times \frac{\lambda}{c}$

T = 25 days