The critical angle between an equilateral prism and air is 45 degrees.if the incident ray is perpendicular to the refracting surface,then what happens?

Question

Anonymous · Accepted Answer

It is totally reflected from the second surface and emerges out perpendicularly from third face into air

Steve · Answer

nothing.

Aiswarya · Answer

So,in the question it is given angle od incidence is 90 degree.(perpendicular to refracting surface ).Now since it is an equateral triangle each angle is 60 degree.As the light touches the 2 nd surface we can see a triangle there with angles 60 degree and 90 degree so obviously the other angle is 30 degree.when we draw a normal we can understand that angle of incidence is 60 degree (90-30) .Given critical angle is 45 degree.here angle of incidence is greater than 45 i.e, 60 degree.so this is the condition for TIR.so it will get reflected to the same medium.Again when the light ray reaches the 3 rd side we can again consider a triangle . calculating the angles we will get angle of refraction ad 90 degree. so it will emerge out perpendicular to the 3 rd surface.
Hope this helps.😊