Question

Define total internal reflection. Explain any two applications of total internal reflection.​

Answer 1

Answer:

Definition:

Total internal reflection, in physics, complete reflection of a ray of light within a medium such as water or glass from the surrounding surfaces back into the medium. The phenomenon occurs if the angle of incidence is greater than a certain limiting angle, called the critical angle. In general, total internal reflection takes place at the boundary between two transparent media when a ray of light in a medium of higher index of refraction approaches the other medium at an angle of incidence greater than the critical angle. For a water-air surface the critical angle is 48.5°. Because indices of refraction depend on wavelength, the critical angle (and hence the angle of total internal reflection) will vary slightly with wavelength and, therefore, with colour. At all angles less than the critical angle, both refraction and reflection occur in varying proportions.

Applications:

Diamond: When the incident ray falls on every face of the diamond such that the angle formed the ray is greater than the critical angle. The critical value of the diamond is 23°. This condition is responsible for the total internal reflection in diamond which makes it shine.

Mirage: It is an optical illusion which is responsible for the appearance of the water layer at short distances in a desert oron the road. Mirage is an example of total internal reflection which occurs due to atmospheric refraction.