JEE Main · 2025 · 03 Apr 2025 · Shift 1 · Wave Optics

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Two coherent monochromatic light beams of intensities 4I and 9I are superimposed. The difference between the maximum and minimum intensities in the resulting interference pattern is xI . The value of

x

is ______ .

Answer: 24

Solution

For two coherent beams the extreme intensities are

I_{m a x} = (I_{1} + I_{2})^{2}

and

I_{m i n} = (I_{1} - I_{2})^{2}

. With

I_{1} = 4 I

and

I_{2} = 9 I

I_{m a x} = (2 I + 3 I)^{2} = 25 I, I_{m i n} = (2 I - 3 I)^{2} = I .

Their difference is

I_{m a x} - I_{m i n} = 25 I - I = 24 I,

x = 24

JEE Main · 2025 · 03 Apr 2025 · Shift 1 · Integer answer

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