A light ray is incident perpendicularly to one face of a `90^circ` prism and is totally internally reflected at the glass-air interface. If the angle of reflection is `45^circ`, we conclude that the refractive index n

Options

A. `ngt(1)/(sqrt2)`
B. `ngtsqrt2`
C. `nlt(1)/(sqrt2)`
D. `nltsqrt2`

Answer

B

Explanation

The incident angle is `45^circ`.
Incident anglegtcriticalandgle,igt`i_c`
`sinigtsini_c`or `sin45gtsini_c` `sini_c=(1)/(n)`
`sin45^circgt(1)/(n)`or`(1)/(sqrt2)gt(1)/(n)impliesngtsqrt2`