Why in total internal reflection,light ray must pass from denser to rarer medium ONLY?

Asked by pb_ckt | 3rd Mar, 2019, 04:00: PM

Expert Answer:

Total internal reflection can only happen when light ray travel from denser medium . by the laws of refraction whenever light ray travel from denser to rarer it get away from the normal . So by changing incident angle at some extent we can make light ray travel along the surface of contact,  this angle is known as critical angle. If we increase the incident angle from critical angle the light won't get refracted anymore, total internal reflection will takes place.
Diagram is attached. 

Answered by Ankit K | 3rd Mar, 2019, 04:53: PM