A ray of light is incident on a block of glass in such a way that the angle between the reflected ray and the refracted ray is `90^(@)` . Determine the relation between the angle of incident and the refraction index of glass.

Explanation

Here angle of incidence = I
`therefore` angle of reflection = I, angle of refraction = r
angle between the reflected ray and the refracted ray = `90^(@)`
According to the Fig. 2.7,
`I + 90^(@) + r = 180^(@)`
or, " "`r = 90^(@) - i`
Refractive index of glass,
`mu = (sini)/(sinr)= (sini)/(sin(90^(@)-i))= (sini)/(cosi) = tani`