Question

A ray of light travelling through glass of refractive index `sqrt2` is incident on glass-air boundary at an angle of incidence 45°. If refractive index of air is 1, then the angle of refraction will be `[sin 45^circ = 1/sqrt2, sin 90^circ = 1]`

Options

• 45°

• 30°

• 60°

• 90°

Answer 1

90°

Explanation:

From Snell's law,

µ_i sin i = µ_r sin r

where, refractive index of glass is µ₁, angle of incidence is i, refractive index of air is µ_r and angle of refraction is r.

Here, `mu_"i" = sqrt2, "i" = 45^circ` and µ_r = 1

`=> (sqrt2) sin 45^circ = (1) sin "r"`

`(sqrt2)(1/sqrt2)` = sin r

⇒ sin r = 1 = sin 90°

r = 90°