Question

why doesn't light bend when it initially enters the glass? what actually happens to the light inside the semi-circle?

Answer 1

when light enters a different substance along the normal ( right angles or 90) it does not bend (refract) but does change velocity.
So with the semi circular block the light can be made to hit the circumference at 90 if it is aimed at the centre of the circle - so it does not bend

Answer 2

light bends at the moment of impact. It doesn't bend on a uniform medium

Answer 3

so what happens to the light inside the semi-circle then

Answer 4

sorry i wouldnt know that one google images for it :)

Answer 5

http://ts1.mm.bing.net/th?id=H.4877705346090080&pid=15.1

Answer 6

thank you