Q. In hydrogen atom, electron makes transition from $n = 4$ to $n = 1$ level. Recoil momentum of the $H$ atom will be
A) $3.4 \times 10^{- 27}N - s$
B) $6.8 \times 10^{- 27}N - s$
C) $3.4 \times 10^{- 24}N - s$
D) $6.8 \times 10^{- 24}N - s$
Explanation
(b) Recoil momentum = momentum of photon $= \frac{h}{\lambda}$
$= hR\left( \frac{1}{n_{1}^{2}} - \frac{1}{n_{2}^{2}} \right) = \frac{hR \times 15}{16} = 6.8 \times 10^{- 27}N \times s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.