How must light travel out of a substance if it is not going to be refracted?

How does the light have to enter the glass?

(a) To produce a large amount of bending?

(b) For no refraction to happen?

How can you bend light away from the normal?

Draw and complete the following diagrams to show what happens to the beams of light as they enter the glass block and then leave it:

What name is given to the ratio of sine of angle of incidence to the sine of angle of refraction?