Q. An electron and photon have same wavelength. If $E$ is the energy of photon and $p$ is the momentum of electron, then the magnitude of $E/p$ in SI unit is
A) $3.33 \times 10^{- 9}$
B) $3.0 \times 10^{8}$
C) $1.1 \times 10^{- 19}$
D) $9 \times 10^{16}$
Explanation
(b) Foe electro, $p = \frac{h}{\lambda};$ and for photon, $E = \frac{hc}{\lambda}$
$\therefore\ \frac{E}{p} = \frac{hc/\lambda}{h/\lambda} = c = 3 \times 10^{8}\ ms^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.