When do we say that the Angle of Incidence is equal to the Critical Angle?

Question

When do we say that the Angle of Incidence is equal to the Critical Angle?

Answer 1

um i ok going back a year, my formula is something like this: Na/Nb=SinB/SinA

SinB=1 at B=90  

ok when the refractive indexes equal 1/Sin Theta where Theta is the angle between the light and the perpendicular.

If ur doing an experiment it is the smallest angle when you no longer see the light coming out the other side or whatever material

Answer 2

When a ray of light traveling in an optically  rarer medium is trying to enter an optically denser  medium, it will be able to enter the denser medium if the angle of incidence is less than the critical angle. If it is more, the ray will undergo total internal reflection. If the angle of incidence is equal to the critical angle, then the emergent ray will graze the common surface of the two mediums.  

Answer 3

when the ray passes through the surface of 2nd medium, without entering it and without reflecting(actually refracting) back, we say that angle of incidense is = critical angle. in other words, when the emerging ray is perpendicular to the normal to the incident plane, we say that angle of incidence=critical angle.

Answer 4

When a ray of light coming from a medium of high index of refraction n1 to a medium of low index of refraction n2 , the critical angle has a value of sinus =n2/n1. For angles of incidence greater when this value the ray undergoes a total reflexion