Two light beams of intensities 4 I and 9 I interfere on a screen. The phase difference between these beams on the screen at point A is zero and at point B is π . The difference of resultant intensities, at the point A and B , will be _____ I .

Question

Two light beams of intensities 4 I and 9 I interfere on a screen. The phase difference between these beams on the screen at point A is zero and at point B is π . The difference of resultant intensities, at the point A and B , will be _____ I .,

MARKS App · Accepted Answer

The resultant intensity is given by I net = I 1 + I 2 + 2 I 1 I 2 cos ϕ Now, for I max , phase angle is ϕ = 0 and for I min , phase angle is ϕ = π . Thus, I max = I 1 + I 2 2 = 9 I + 4 I 2 = 25 I And I min = I 1 - I 2 2 = 9 I - 4 I 2 = I The difference of resultant intensities is I max - I min = 25 I - I = 24 I

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