Question

A magnetic field exerts no force on:

(a) an electrical charge moving perpendicular to its direction
(b) an unmagnetised iron bar
(c) a stationary electric charge
(d) a magnet

Answer 1

(c) a stationary electric charge
Magnetic force is given by Lorentz equation as:
F = q (v $\times$ B)
Here, q = amount of electric charge, v = velocity of charge and B = magnetic flux
Thus, when velocity of charge​ (v) = 0, magnetic force (F) = 0