what is critical angle

Angle of incidence for which angle of reflection is 90

the angle of incidence beyond which rays of light passing through a denser medium to the surface of a less dense medium are no longer refracted but totally reflected. is called critical angle
Thanks & Regards
Mukesh Sharma
AskIITians Faculty

Critical angle is that at which incident ray in a denser medium is refracted perpendicularly to surface to less dense medium.Beyond that angle,TIR phenomenon takes place

the angle of incidence for which the angle for which the angle of reflection is 90 degree is called as critical angle.