CBSE Class 10 Answered

Hi dear,

• when the ray exiting the optically denser material is refracted to such an extent that it is bent to 90° from the normal.
• The angle of incidence in this special case is called the critical angle because beyond this point, there is a difference in the behavior of the light.
• When the critical angle for the two substances is exceeded, a phenomenon known as total internal reflection, or T.I.R. occurs.
• This means that instead of exiting the optically denser material and being refracted, the incident ray is reflected inside the material (i.e. internally).After this point, normal laws of reflection are followed, by the ray, off of the surface between the two materials.Hope this helps.