Q. Which of the following is correctly matched?
A) Momentum of H atom when electrons return from $n = 2$ to $n = 1:\frac{3Rh}{4}$
B) Momentum of photon : Independent of wavelength of light
C) $e/m$ ratio of anode rays : Independent of gas in the discharge tube
D) Radius of nucleus : $(Mass\ no.)^{1/2}$
Explanation
(a)
$\frac{1}{\lambda} = R\left\lbrack \frac{1}{1^{2}} - \frac{1}{2^{2}} \right\rbrack = \frac{3R}{4}$
$\lambda = \frac{h}{p}$
$P = \frac{h}{\lambda} = h \times \frac{3R}{4} = \frac{3Rh}{4}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.