The refractive index of a prism for a monochromatic wave is `sqrt(2)` and its refracting angle is `60^(@)` for minimum deviation, the angle of indidence will be

Options

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

Answer

B

Explanation

`n = (sin ((A + delta_(m))/(2) ))/(sin A//2) rArr sqrt(2) = (sin ( (60^(@) + delta_(m) )/(2) ) )/(sin 30^(@) ) `
`rArr (60^(@) + delta_(m))/(2) = 45^(@) rArr delta_(m) = 30^(@)`
`delta_(m) = 2i - A rArr i= (60^(@) + 30^(@) )/(2) = 45^(@)` .