NEET-XII-Physics
17: Light Waves
- #12Find the thickness of a plate which will produce a change in optical path equal to half the wavelength λ of the light passing through it normally. The refractive index of the plate is μ.Ans : Given:
The refractive index of the plate is `` \mu ``.
Let the thickness of the plate be 't' to produce a change in the optical path difference of `` \frac{\lambda }{2}``.
We know that optical path difference is given by `` \left(\,\mathrm{\,\mu \,}-1\right)t``.
`` \therefore \left(\,\mathrm{\,\mu \,}-1\right)t=\frac{\lambda }{2}``
`` \Rightarrow t=\frac{\lambda }{2\left(\,\mathrm{\,\mu \,}-1\right)}``
Hence, the thickness of a plate is `` \frac{\lambda }{2\left(\,\mathrm{\,\mu \,}-1\right)}``.
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