Question

The electron performs circular motion of radius r, perpendicular to a uniform magnetic field B. The kinetic energy gained by this electron in half the revolution is ___________.

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

Answer 1

Answer: (C)

Zero

Since,Electron will move perpendicular to the magnetic field, the work done by magnetic field will be zero and there will not be any change in kinetic energy,So kinetic energy gained by electron will be $zero$.

Therefore, C is the correct option.