Please answer the question below in the comment box.
1) How would critical angle of a rectangle glass block change when we
a) increase the thickness of the glass block;
b) increase the angle of incidence of the ray exiting the glass block;
c) change the material of the rectangle glass block to another of higher refractive index?
2) What are the main concept(s) learnt for today's lesson? Give at least 3 of them.