The diffraction pattern of a light of wavelength $400 \mathrm{~nm}$ diffracting from a slit of width $0.2 \mathrm{~mm}$ is focused on the focal plane of a convex lens of focal length $100 \mathrm{~cm}$. The width of the $1^{\text {st }}$ secondary maxima will be :
Solution
<p>Width of $1^{\text {st }}$ secondary maxima $=\frac{\lambda}{a} \cdot D$</p>
<p>Here</p>
<p>$$\begin{aligned}
& a=0.2 \times 10^{-3} \mathrm{~m} \\
& \lambda=400 \times 10^{-9} \mathrm{~m} \\
& D=100 \times 10^{-2}
\end{aligned}$$</p>
<p>Width of $1^{\text {st }}$ secondary maxima</p>
<p>$$\begin{aligned}
& =\frac{400 \times 10^{-9}}{0.2 \times 10^{-3}} \times 100 \times 10^{-2} \\
& =2 \mathrm{~mm}
\end{aligned}$$</p>
About this question
Subject: Physics · Chapter: Optics · Topic: Reflection and Mirrors
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