Will there be a 'partially reflected ray' at critical angle of incidence? enter image description here

This diagram is given in my textbook. There are 'partially reflected rays' when the 'angle of incidence' is less than 'critical angle'. But when the 'angle of incidence' is equal to 'critical angle', there are no 'partially reflected rays'. Is this correct?

I checked youtube for a real demonstration and found this video: https://www.youtube.com/watch?v=NAaHPRsveJk

It shows a 'partially reflected ray' even at critical angle, which then becomes the 'totally reflected ray' for higher incidence angles.


1 Answer 1


You are right. The reflected beam is always there. It is just that when incident angle becomes equal to the critical one, the intensity of the reflected beam becomes equal to the incident one, and then stays that way as you increase the incident angle further.

The choice to not to draw the reflected beam at the critical incident angle is purely a figure design issue. Probably to not to overcrowd the figure.


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