A ray of light travelling in a transparent medium of refractive index n falls, on a surface separating the medium from air at an angle of incidents of `45^@`. The ray can undergo total internal reflection for the following n,

Options

A. n = 1.25
B. n = 1.33
C. n = 1.4
D. n = 1.5

Answer

A

Explanation

For total internal reflection
`sinigtsinc " " "where, i - angleof incidence"`
`But, sinc=(1)/(n) " " "c-cirtical angle"`
`sinigt(1)/(n)`
`n gt (1)/(sin i)`
`ngt(1)/(sin45),ngtsqrt(2),ngt1.414`