Question

Explain the following, giving proper reason : (a) During charging of a capacitor, displacement current exists in the capacitor. But there is no displacement current when it gets fully charged. (b) The frequency of microwaves in ovens matches with the resonant frequency of water molecules. (c) Infrared waves are also known as heat waves.

(i) Monochromatic light is incident on a surface separating two media. The frequency of the light after refraction remains unaffected but its wavelength changes. Why? (ii) The frequency of an electromagnetic radiation is 1.0 × 10¹¹ Hz. Identify the radiation and mention its two uses.