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MHT CET 202626 AprilMorning Shift
Exam
MHT CET
Year
2026
Date
26 April
Shift
Morning Shift
Subject
Physics
Chapter
Wave Optics

MHT CET 2026 · 26 April · Morning Shift · Physics · Wave Optics

In the Young's double slit experiment, the intensity of light at a...

In the Young's double slit experiment, the intensity of light at a point on the screen is 'K', λ\lambda being the wavelength of light used. The intensity at a point where path difference is λ6\dfrac{\lambda}{6} will be \left[\cos \left(\dfrac{\pi}{6}\right) = \dfrac{\sqrt{3}}{2}\right]

Options

  1. AK6\dfrac{K}{6}
  2. BK4\dfrac{K}{4}
  3. CK2\dfrac{K}{2}
  4. D3K4\dfrac{3K}{4}

Correct answer

D. 3K4\dfrac{3K}{4}

Step-by-step solution

The maximum intensity in Young's double slit experiment is given as I_\max = K.

The phase difference ϕ\phi is related to the path difference Δx\Delta x by the formula:

ϕ=2πλΔx\phi = \dfrac{2\pi}{\lambda} \Delta x

Given the path difference Δx=λ6\Delta x = \dfrac{\lambda}{6}, the phase difference is:

ϕ=2πλ×λ6=π3\phi = \dfrac{2\pi}{\lambda} \times \dfrac{\lambda}{6} = \dfrac{\pi}{3}

The intensity II at any point on the screen is given by:

I = I_\max \cos^2\left(\dfrac{\phi}{2}\right)

Substituting the values of I_\max and ϕ\phi:

I=Kcos⁡2(π6)I = K \cos^2\left(\dfrac{\pi}{6}\right)

Since cos⁡(π6)=32\cos\left(\dfrac{\pi}{6}\right) = \dfrac{\sqrt{3}}{2}, we get:

I=K(32)2=3K4I = K \left(\dfrac{\sqrt{3}}{2}\right)^2 = \dfrac{3K}{4}

Answer: 3K4\dfrac{3K}{4}
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