What is the force experienced by an electron moving with velocity of 0.5c in a magnetic field $\vec{B}$ of 2T? The angle between the velocity vector and $\vec{B}$ is 90°.

(c is the velocity of light, $e=1.6 \times 10^{-19} C$)

$4.8 \times 10^{-12} N$

The correct answer is Option (3) → $4.8 \times 10^{-12} N$

Since the angle between the velocity vector and magnetic field is 90°, the force is at its maximum.

$F=|q|vB$ [Lorentz force]

$=(1.6×10^{-19})×(1.5×10^8)×2$

$=4.8×10^{-11}N$