Question #23b53

1 Answer
Apr 20, 2014

One of the most dramatic forms of total internal reflection is what causes light to bounce around inside a diamond and increase its brilliance.

It can be observed when you are swimming underwater and you attempt to see someone standing on the edge of the pool. If you are a good distance away, making a large angle of incidence, then you will not be able to see the person, because the light will be internally reflected off the boundary of the water. Moving closer makes the angle of incidence smaller and then you can see the person.

Here's a challenge for you - see if you can figure out (based on the above, and your other readings on total internal reflection) why this works. Place a coin under an empty water glass. Start to fill the glass with water. Watch the coin "disappear" as you view it from the side. (If you look down from above, the coin is visible.)