Question

A ray moving in water at 55.5 deg
enters plastic, where it bends to
48.7 deg. What is the index of
refraction for the plastic?
( water n = 1.33, Air n = 1.00 )

Answer 1

Answer:

Refractive index of the plastic = 1.46

Explanation:

By Snell's law,

$\frac{\text{sin}\theta _{2} }{\text{sin}\theta _{1}}=\frac{n_1}{n_2}$

Here, $\theta _1$ = Angle of incidence in medium 1 (Plastic)

$\theta_2$ = Angle of refraction in medium 2 (Water)

$n_1$ = Refractive index of medium 1 (Plastic)

$n_2$ = Refractive index of medium 2 (Water)

By substituting values in the formula,

$\frac{\text{sin}(48.7)}{\text{sin}(55.5)}=\frac{1.33}{n_2}$

$n_2=\frac{1.33\times \text{sin}(55.5)}{\text{sin}(48.7)}$

    = 1.46

Therefore, refractive index of the plastic = 1.46