Question:
A light beam is described by $E=800 \sin \omega\left(t-\frac{x}{c}\right)$
. An electron is allowed to move normal to the propagation of light beam with a speed of $3 \times 10^{7}$ $\mathrm{ms}^{-1}$. What is the maximum magnetic force exerted on the electron?
Correct Option: , 4
Solution:
$\frac{\mathrm{E}_{0}}{\mathrm{C}}=\mathrm{B}_{0}$
$\mathrm{F}_{\max }=\mathrm{eB}_{0} \mathrm{~V}$
$=1.6 \times 10^{-19} \times \frac{800}{3 \times 10^{8}} \times 3 \times 10^{7}$
$=12.8 \times 10^{-18} \mathrm{~N}$
Ans. 4