A ray of light travelling in a transparent medium f refractive index `mu`, falls on a surface separating the medium from air at an angle of incidence of `45^(@)`. For which of the following value of `mu` the ray can undergo total internal reflection ?

Options

A. `mµ = 1.50`
B. `mµ = 1.25`
C. `mµ = 1.33`
D. `mµ = 1.10`

Answer

A

Explanation

From Snell.s law,
`(sini_(c))/(sin90^(@))=(1)/(mu)`
`mu=(1)/(sin45^(@))=sqrt2=1.41`
`therefore" for condition of total internal reflection"`
`sini gt sin i_(c)`
`sin 45^(@) gt (1)/(mu)`
`mu gt (1)/(sin 45^(@))=sqrt2`
`mu gt 1.41`
For the refractive index 1.50 total internal reflection will occur.