Q. Due to Doppler’s effect, the shift in wavelength observed is $0.1\mathring{\mathrm{A}}$ for a star producing wavelength $6000\mathring{\mathrm{A}}$. Velocity of recession of the star will be
A) $2.5\ km/s$
B) $10\ km/s$
C) $5\ km/s$
D) $20\ km/s$
Explanation
(c) $\frac{\Delta\lambda}{\lambda} = \frac{v}{c}\therefore v = \frac{\mathrm{\Delta}\lambda}{\lambda}c = \frac{0.1}{6000} \times 3 \times 10^{5}km/s = 5\ km/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.