(a) Name the e.m. waves which are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves. (b) If the Earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain. (c) An e.m. wave exerts pressure on the surface on which it is incident. Justify.

CBSE Sample Question Paper, Class 12 Physics Term 2 Question - (a) Name the e.m. waves which are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves. (b) If the Earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain. (c) An e.m. wave exerts pressure on the surface on which it is incident. Justify.

(a) Name the e.m. waves which are suitable for radar systems used in aircraft navigation. Write the range of frequency of these waves.
(b) If the Earth did not have atmosphere, would its average surface temperature be higher or lower than what it is now? Explain.
(c) An e.m. wave exerts pressure on the surface on which it is incident. Justify.

ANS 11.
(a) Microwaves are suitable for the radar system used in aircraft
navigation. Range of frequency of microwaves is 108 Hz to 1011 Hz.
(b) If the Earth did not have atmosphere, then there would be absence
of greenhouse effect of the atmosphere. Due to this reason, the temperature of the earth would be lower than what it is now.
(c) An e.m. wave carries momentum with itself and given by
P = Energy of wave(U)/ Speed of the wave(c)
= U/c when it is incident upon a surface it exerts pressure on it.