Question

State two properties of electromagenetic waves. How can we show that em waves carry momentum?

Answer 1

Properties of electromagnetic waves:

(i) Transverse nature.

(ii) Does not get deflected by electric or magnetic fields.

(iii) Same speed in vacuum for all waves.

(iv) No material medium required for propagation.

(v) They get refracted, diffracted and polarised.

Electric charges present on a plane, kept normal to the direction of propagation of an em wave can be set and sustained in motion by the electric and magnetic field of the elecromagnetic wave. The charges thus acquire energy and momentum from the waves.