NEET-XII-Physics
17: Light Waves
- #39Plane 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°.Ans : 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 \,\mathrm{\,sin\,}30°=1\times \,\mathrm{\,\lambda \,}``
`` \Rightarrow \lambda =\frac{5}{2}=2.5\,\mathrm{\,cm\,}``
Therefore, the wavelength of the microwaves is 2.5 cm.
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