So what do we see when we look at refracted light? We won’t be able to see how the light ray was travelling before it bends – we can only see the light ray after it bends and travels to our eyes.

If you were to look at the prism at eye level, the light ray would appear to be coming out from the right side of the block instead of the middle. This is an optical illusion.

Just like in reflection, the image can be found where the virtual ray begins, while the actual object is found where the real ray begins.

 

Looking Into Water

In this example (and the one below) we will use two light rays coming  from an object and heading towards the eye at a small angle apart. We referred to this earlier as a light cone.

As the bird looks into the water it sees the fish. As light has refracted at the surface the above two lines show the actual path each light ray has taken.

Drawing virtual rays back along the paths of the rays entering the bird’s eye, we can determine the apparent position of the fish.

We can see the fish appears to be nearer to the surface than it actually is.

What does the bird have to do when diving into the water to catch the fish?

 

You have probably stood near the edge of a swimming pool and then jumped in only to realise that it is actually much deeper than it looked.

 

Looking Out of Water

For the fish looking out of the water at the bird the opposite is true. Again we start by drawing a light cone from the bird heading towards the fishes eyes.

This time we follow the rays that are going into the fishes eyes and locate the virtual position of the bird.
It is further away from the fish that the actual bird.

 

<< Back

Refraction

Next >>