Wave Mechanics Question 1097

Question: If separation between screen and source is increased by 2% what would be the effect on the intensity

[CPMT 2003]

Options:

A) Increases by 4%

B) Increases by 2%

C) Decreases by 2%

D) Decreases by 4%

Show Answer

Answer:

Correct Answer: D

Solution:

$ I\propto \frac{1}{r^{2}} $

Therefore $ \frac{\Delta I}{I}=-2\frac{\Delta r}{r} $ =$ -,2\times 2=-,4,% $ Hence intensity is decreased by 4%.