I am an Electrical Engineer graduated from BUET. I have been studying and practicing Physics for quite a long time now. I have opened this website to share my thoughts on a few topics of the subject. Below I have talked about total internal reflection.
You know when a ray of light passes from a denser medium to a lighter medium it deviates from the normal. That means the refraction angle is greater than the incident angle. So there is a value of the incident angle for which the refraction angle will be 90o, i.e. the rays of light pass along the surface which separates the two media instead of entering the lighter medium. This particular angle is called the critical angle for the two media.
When the incident angle is even greater the critical angle, no refraction takes place. Instead reflection takes place. This particular type of reflection is called total internal reflection. It is called so because in this type of reflection all the incident rays are reflected, no rays are absorbed or refracted. Which is why this type of reflection is better than normal reflection. As a result the object looks brightest on the reflection surface.