Wave Optics

JEE Main level, single correct, medium

78 of 191

Question 78 of 191

In young's double slit experiment performed using a monochromatic light of wavelength λ\lambda, when a glass plate (μ=1.5)\left(\mu =1.5\right) of thickness xλx\lambda is introduced in the path of the one of the interfering beams, the intensity at the position where the central maximum occurred previously remains unchanged. The value of xx will be

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Answer: (B) 22

Since the intensity at the central maxima remains unchanged, the change in the path difference should be an integral multiple of the wavelength. Therefore,
Δx=(μ−1)t=nλ\Delta x=\left(\mu -1\right)t=n\lambda⇒(1.5−1)xλ=nλ\Rightarrow \left(1.5-1\right)x\lambda =n\lambda⇒x=n0.5=2n\Rightarrow x=\dfrac{n}{0.5}=2n
For n=1n=1
x=2x=2

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