प्रिज्म का अपवर्तनांक कोण A तथा उसके पदार्थ का अपवर्तनांक `cot ""(A)/(2)` है | न्यूनतम विचलन कोण है

Options

A. `180^(@) - 3A `
B. `180^(@) + 2A `
C. `90^(@) - A `
D. `180^(@) - 2A `

Answer

D

Explanation

`mu = (sin""(A+delta_(m))/(2))/(sin""(A)/(2)) rArr cot ""(A)/(2) = (sin""(A+delta_(m))/(2))/(sin""(A)/(2))`
`rArr (cos""(A)/(2))/(sin""(A)/(2)) = (sin""(A+delta_(m))/(2))/(sin""(A)/2)`
`rArr sin(90^(@) -(A)/(2)) = sin((A + delta_(m))/(2)) rArr delta_(m) = 180-2A`