The smallness of the critical angle θc for diamond means that light is easily "trapped" within a diamond and eventually emerges from the many cut faces. This makes a diamond more brilliant than stones with smaller n and larger θc. Traveling inside a diamond, a light ray is incident on the interface between diamond and air. What is the critical angle for total internal reflection? The refraction index for diamond is 2.23 . Answer in uni

26.6°

Explanation:

refractive index of diamond, n = 2.23

When a ray of light passes from denser medium to the rarer medium and refracts at an angle of 90 degree from the normal of the surface, such angle of incidence in the denser medium is called the critical angle.

By the Snell's law

For critical angle, angle of incidence is critical angle, i = θc and angle of refraction, r = 90

So,

Sin θc / Sin 90 = 1 / 2.23

Sin θc = 0.448

θc = 26.6°

Thus, the critical angle is 26.6°.