Ray Optics

JEE Main level, single correct, medium

264 of 295

Question 264 of 295

The variation of refractive index of a crown glass thin prism with wavelength of the incident light is shown. Which of the following graphs is the correct one, if DmD_{m} is the angle of minimum deviation?

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Answer: (A)

When angle of prism is small, then angle of deviation

is given by Dm=(μ−1)A\mathrm{D}_{\mathrm{m}}=(\mu-1) \mathrm{A}

So, if wavelength of incident light is increased, μ\mu decreases

and hence Dm\mathrm{D}_{\mathrm{m}} decreases.

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