CBSE Class 12 Physics 2023 Outside Delhi Set 3 Paper

Question : 11 of 13

Marks: +1, -0

SECTION - C

A ray of light is refracted by a glass prism. Obtain an expression for the refractive index of the glass in terms of the angle of prism

A

and the angle of minimum deviation

8 {\m}

Solution:

A ray is refracted by a glass prism.

Angle of deviation

=δ=i_1+i_2+A

Angle of prism

=A=r_1+r_2

For minimum deviation,

\;i_1\;=i_2 \;\text " and "\; r_1=r_2

\; ∴ \;δ_{\min }\;=2 i_1-A

\; ∴ \;i_1\;=\;{A+δ_m}/{2}

\;\;\text " Also, "\;\;A\;=2 r_1

\; ∴ \;r_1\;=\;{A}/{2}

\; ∴ \;\;\text " Refractive index "\;\;=µ

\;=\;{ sin \;i_1}/{ sin \;r_1}=\;{ sin \;{A+δ_m}/{2}}/{ sin \;\;{A}/{2}}

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