Question

Calculate the work done on electron beam which is moving in a magnetic field ?

• A. 2 times of product of electronic charge and the magnetic field
• B. Product of Square of charge and magnetic field
• C. Product of electronic charge and the magnetic field
• D. Zero

Answer 1

The correct option is D Zero

Electron beam is moving in a magnetic field. Work done is given by:
$W=\overrightarrow{F}.\overrightarrow{s}$
or, $W=\overrightarrow{F}.\overrightarrow{v}t=0$
Since, magnetic force is always perpendicular to the velocity of the particles. Particle actually moves in a circle.