Explain the term (i) ground wave and (ii) sky wave.

Explanation

(i) The amplitude modulated radio waves which
are travelling directly following the surface of
the earth are known as ground waves or surface
waves. These waves can have frequency upto
1710 kHz. The ground waves can bend round
the corners of the objects on earth and hence
their intensity falls with distance.
(ii) The amplitude modulated radio waves of
frequency 3M hz to 30 MHz, which are received
after being reflected from the ionosphere are
called as sky waves.