# Refractive index, light ray help

1. Oct 21, 2007

### schutzeh

Hi, this is the question in my homework.

Explain what happens when a light ray enters and leaves a glass block if it hits the face of the block at right angles to it.

Can someone pelase help me, i think that the light ray would just go straight through the block without bending but im unsure and it requires a more in depth answer than that so if anyone can, its greatly appreciated.

Thanks

2. Oct 21, 2007

### Staff: Mentor

Refraction is governed by Snell's law. Look it up and see what it says about this situation.

3. Oct 22, 2007

### rl.bhat

Yes. The light will travel through the glass block without bending. But its path inside the block gets shortened.
Apparent path = real path /refractive index
If you see the source of light from the other side of the block , you feel that the source of light is nearer.

4. Oct 22, 2007

### Staff: Mentor

That's true when viewing a light source (and is also explained by Snell's law), but this question only refers to a single ray that makes a right angle to the surface. A light source will have many rays at all angles.

To answer this question, apply Snell's law.