Question

An electron performs circular motion of radius $r$, perpendicular to a uniform magnetic field $B$. The kinetic energy gained by this election in one revolution is _______

• A. $\frac{1}{2}m{v}^2$
• B. zero
• C. $\frac{1}{4}m{v}^2$
• D. $\pi rBeV$

Answer 1

The correct option is B zero

When an electron performs circular motion of radius '$r$' to a uniform magnetic field $B$, its speed is constant and only direction is changing.

$\therefore r=\frac{mv}{eB}v=\frac{reB}{m}=constant$

$\therefore$Kinetic energy gain=0(zero)