The sound of frequency above 20kHz is called :

The bouncing of light from a surface of a body is called :

Light ray which strikes the surface is called :

The voice box of human being is called :

The light deviated away from the normal when it passes from :

For total internal reflection :

The angle in between the reflected ray and the normal drawn from the point of incidence is called :

For critical angle the angle of refraction is :

Which of the following produces pleasant sound?

The principle behind the working of optical fiber is :