Question
Out of the following options which one can be used to produce a propagating electromagnetic wave?
A.
A stationary charge
B.
A chargeless particle
C.
An accelerating charge
D.
A charge moving at constant velocity
Answer :
An accelerating charge
Solution :
A particle is known that an electric charge at rest has electric field in the region around it, but no magnetic field. A moving charge produces both the electric and magnetic fields. If a charge is moving with a constant velocity, the electric and magnetic fields will not change with time, hence no $$EM$$ wave will be produced. But if the charge is moving with a non-zero acceleration, both the electric and magnetic field will change with space and time, it then produces $$EM$$ wave. This shows that accelerated charge emits electromagnetic waves.