Answer the following
(a) Name the em waves which are used for the treatment of certain forms of cancer. Write their frequency range.
(b) This ozone layer on top of stratosphere is crucial for human survival. Why?
(c) Why is the amount of the momentum transferred by the em waves incident on the surface so small?

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Solution

(a) Gamma $(γ)$ rays are used for the treatment of certain forms of cancer. Their frequency range is $3 \times 10^{19} H z$ to $5 \times 10^{24} H z$ .
(b) The thin ozone layer on top of stratosphere absrob most of the harmful ultraviolet rays coming from the sun towards the Earth. They include UVA, UVB and UVC radiations, which can destroy the life system on the Earth. Hence, this layer is crucial for human survival.
(c) Momentum transferred $=$ Energy Speed of light
$= h ν c = 10^{- 22}$ (for $ν$ = 1020 Hz)
Thus, the amount of the momentum transferred by the em waves incident on the surface is very small.

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