Wave Optics

JEE Main level, single correct, medium

130 of 191

Question 130 of 191

A microwave of wavelength 2.0cm2.0cm falls normally on a slit of width 4.0cm.4.0cm. The angular spread of the central maxima of the diffraction pattern obtained on a screen 1.5m1.5m away from the slit, will be:

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Answer: (C) 60º60º

In diffraction, for first minima asin⁡θ=λa\sin \theta =\lambda
⇒sin⁡θ=λa=12\Rightarrow \sin \theta =\dfrac{\lambda }{a}=\dfrac{1}{2}
⇒θ=30∘\Rightarrow \theta =30^{\circ}
Therefore, angular spread of central maxima will be =2θ=60º=2\theta =60º.

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