The two light beams having intensities I and 9I interfere to produce a fringe pattern on a screen. The phase difference between the beams is $\pi$/2 at point P and $\pi$ at point Q. Then the difference between the resultant intensities at P and Q will be :
Solution
<p>${I_P} = I + 9I + 2\sqrt {I \times 9I} \cos {\pi \over 2} = 10I$</p>
<p>${I_Q} = I + 9I + 2\sqrt {I \times 9I} \cos \pi = 4I$</p>
<p>So, ${I_P} - {I_Q} = 6I$</p>
About this question
Subject: Physics · Chapter: Optics · Topic: Reflection and Mirrors
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