Question

when will be the critical angle maximum ?

Answer 1

Hello!

Total Internal Reflection takes place when the angle of incidence reaches a critical angle (i_c) and the angle of refraction equals 90^o. That critical angle depends upon the two mediums or the refractive indices of the two mediums.

It is however impossible when the critical angle would reach its maximum, however its value would be very close to 90^o.