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Question
Plane microwaves are incident on a long slit of width 5.0 cm. Calculate the wavelength of the microwaves if the first diffraction minimum is formed at θ = 30°.
Solution
Given:-
Width of the slit, b = 5.0 cm
First diffraction minimum is formed at θ = 30°.
For the diffraction minima, we have
`bsinθ = nλ`
For the first minima, we put n = 1.
\[5 \times \sin30^\circ = 1 \times \lambda\]
\[ \Rightarrow \lambda = \frac{5}{2} = 2 . 5 cm\]
Therefore, the wavelength of the microwaves is 2.5 cm.
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