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Question

Physics Question on Refraction of Light

The angle of incidence for a ray of light at a refracting surface of a prism is 4545^{\circ}. The angle of prism is 6060^{\circ }. If the ray suffers minimum deviation through the prism, the angle of minimum deviation and refractive index of the material of the prism respectively, are :

A

30;230^{\circ} ; \sqrt{2}

B

45;245^{\circ} ; \sqrt{2}

C

30;1230^{\circ} ; \frac{1}{ \sqrt{2}}

D

45;1245^{\circ} ; \frac{1}{ \sqrt{2}}

Answer

30;230^{\circ} ; \sqrt{2}

Explanation

Solution

i=45;A=60;δm=2iA=30i = 45^{\circ} ; A = 60^{\circ} ; \delta_m = 2i - A = 30^{\circ}
μ=sin(A+δm2)sinA/2=sin45sin30=12.21=2\mu = \frac{\sin\left(\frac{A + \delta_{m}}{2}\right)}{\sin A/2} = \frac{\sin45^{\circ}}{\sin30^{\circ}} = \frac{1}{\sqrt{2}}. \frac{2}{1} = \sqrt{2}