When an electric charge (q) is kept at rest in a magnetic field, no force acts on it. At the same time, if the charge moves in the magnetic field, it experiences a force. This force is different from Coulomb force, studied in unit 1. This force is known as magnetic force. It is given by the equation

$$ \vec{F} = q \vec{v} \times \vec{B} \quad (3.54) $$

In general, if the charge is moving in both the electric and magnetic fields, the total force experienced by the charge is given by

$$ \vec{F} = q(\vec{E} + \vec{v} \times \vec{B}) $$

It is known as Lorentz force.