Q. The velocity of an electron must possess to acquire a momentum equal to the photon of wavelength 5200 $A^{{^\circ}}$, will be
A) $1398\ ms^{- 1}$
B) $1298\ ms^{- 1}$
C) 1400$\ ms^{- 1}$
D) 1300$\ ms^{- 1}$
Explanation
(c)
$\lambda = \frac{h}{mv}$
$\therefore mv = \frac{6.626 \times 10^{- 34}}{5200 \times 10^{- 10}} = 1.274 \times 10^{- 27}$
For electron, $m = 9.1 \times 10^{- 31}$kg
$9.1 \times 10^{- 31} \times v = 1.274 \times 10^{- 27}$
$v = 1400$ m/s
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.