Question

A beam of light passes from air into a substance X . If the angle of incidence be 72° and the angle of refraction be 40°, calculate the refractive index of substance X ?​

Answer 1

Answer:

Given: sin72∘=0.951 and sin40∘=0.642) Thus, the refractive index of substance X is 1.48.

Answer 2

Given :

Angle of incidence = 72°

Angle of refraction = 40°

To find :

The refractive index of substance X.

Solution :

Using Snell's law of refraction,

According to Snell's law of refraction of light,

The ratio of sine of angle of incidence to the sine of angle of refraction is constant for a given pair of media that is,

$\boxed{ \bf \dfrac{sin \: i}{sin \: r} = constant}$

where,

sin i denotes sine of angle of incidence and sin r denotes sine of angle of refraction.

Substituting the given values in the formula,

$\leadsto \sf n = \dfrac{sin \: i}{sin \: r}$

$\leadsto \sf n = \dfrac{sin \: 72 \degree}{sin \: 40 \degree}$

sin 72° = 0.951 and sin 40° = 0.642

$\leadsto \sf n = \dfrac{0.951}{0.642}$

$\leadsto \sf n = 1.48$

thus, the refractive index of substance X is 1.48