A free electron i A. along the electric field

B. along the magnetic field

C. along the direction of propagation of the wave

D. in a plane containing the magnetic field and the direction of propagation.

Explanation: A particle placed in and electromagnetic wave moving

with velocity v experiences a force called Lorentz’s force due to the

electric and magnetic fields. The force is given as

where q is the charge of the particle, E is the electric field, v is the

velocity of the particle and B is the magnetic field.

An electron at rest is placed in the path of a plane electromagnetic wave. The Lorentz force acting on the electron will be

where e is the charge of the electron. As the electron is at rest so the velocity will be 0. The net Lorentz’s force will be

The electron will move in the direction of the field.