While I am studying Grifiths Electrodynamics I came across this in the Maxwell's laws of Electromagnetic Waves that the electric and magnetic fields of light can effect the charge.

Imagine a single charge in the space devoid of all the interactions(Electric) at rest so that it is not affected by magnetic fields(may be situated at the null point) now if I shine light on that charge will it experience the force?

If it experiences the force then the net electric field in that region changes and according to the Gauss law the flux will change and consequently the charge enclosed should change. If that happens where is the charge going against the conservation of charge.

Someone help me to understand this.


1 Answer 1


The charge will obviously feel a force due to the oscillating electric component of the electromagnetic wave. The mistake you made here, was to assume that a change in the electric field leads to a change in flux. This is not always true. Consider any sphere around our test charge. Since the electromagnetic wave passes through this sphere, its flux is clearly zero(since it passes through). Thus the flux in this sphere is still just that due to the charge enclosed alone.


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