Question

How are electromagnetic waves produced? What is the source of the energy carried by a propagating electromagnetic wave?
Identify the electromagnetic radiations used
(i) In remote switches of a household electronic device; and
(ii) as a diagnostic tool in medicine

Answer 1

According to Maxwell’s theory accelerated charges radiate electromagnetic waves. Consider a charge oscillating with some frequency. (An oscillating charge is an example of accelerating charge.) This produces an oscillating electric field in space, which produces an oscillating magnetic field, which in turn, is a source of the oscillating electric field, and so on. he oscillating electric and magnetic fields thus regenerate each other, so to speak, as the wave propagates through space. The frequency of the electromagnetic wave naturally equals the frequency of oscillation of the charge. The energy associated with the propagating wave comes at the expense of the energy of the source –the accelerated charge.

The electromagnetic radiation used are :
(1) Infrared rays
(2) X-rays