Define TIR and write the conditions for TIR. Derive a relation between critical angle and the refractive index of the medium. Also explain the working of isosceles triangle and optical fiber.

If angle of incidence is more than critical angle then incident ray is totally reflected back into same medium is called total internal reflection. conditions a) incident ray should travel in denser medium and refracted ray should travel in rarer medium .b) angle of incidence is should be greater than critical angle for pair of media in contact.