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Question: Answered & Verified by Expert
In Young's double slit experiment the intensity at a point on the screen is $K$, where path difference is $\lambda$. What will be the intensity at the point where path difference is $\frac{\lambda}{4}$ ?
PhysicsWave OpticsMHT CETMHT CET 2022 (08 Aug Shift 1)
Options:
  • A $\frac{K}{4}$
  • B $\frac{K}{2}$
  • C $K$
  • D 0
Solution:
1077 Upvotes Verified Answer
The correct answer is: $\frac{K}{2}$
$I=2 I_0(1+\cos \phi)$
$\phi=\frac{2 \pi x}{\lambda}$, where $x$ is the path as difference.
$\therefore K=2 I_0\left(1+\cos \left(\frac{2 \pi}{\lambda} \times \lambda\right)\right)=4 I_0$
Now, for path difference $\frac{\lambda}{4}$
$\begin{aligned}
& K^{\prime}=2 I_0\left(1+\cos \left(\frac{2 \pi}{\lambda} \times \frac{\lambda}{4}\right)\right)=2 I_0 \\
& \therefore K^{\prime}=\frac{K}{2}
\end{aligned}$

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