A prism is made up of material of refractive index 'sqrt(3)' . The angle of the prism is A. If the angle of minimum deviation is equal to angle of the prism, then the value of A is

Options

A. `30^@`
B. `45^@`
C. `60^@`
D. `75^@`

Answer

C

Explanation

From Snell’s law,
` mu = sin((A+D_(m))/2)/(sin(A/2))=(2sin(A/2)cos(A/2))/(sin(A/2))`
`(because A=D_(m))`
`sqrt(3)=2cos(A/2)`
`implies cosA/2=sqrt(3)/2`
`A/2=cos^(-1)(sqrt(3)/2)`
`therefore A=60`