JEE Main · 2021 · 27 Aug 2021 · Shift 2 · Wave Optics

The light waves from two coherent sources have same intensity

I_{1} = I_{2} = I_{0}

. In interference pattern the intensity of light at minima is zero. What will be the intensity of light at maxima?

(A) $I_{0}$
(B) $2 I_{0}$
(C) $5 I_{0}$
(D) $4 I_{0}$ ✓ Correct

Answer: (D)

Solution

For two coherent beams of equal intensity

I_{0}

the resultant intensity is

I = 2 I_{0} (1 + cos ϕ)

. The minima, at

ϕ = π

, give

I = 0

, consistent with the stated zero minimum, while the maxima occur at

ϕ = 0

I_{m a x} = 2 I_{0} (1 + 1) = 4 I_{0} .

The intensity at the maxima is

4 I_{0}

JEE Main · 2021 · 27 Aug 2021 · Shift 2 · Single correct option

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