Transparency of water
Question:
Some time ago a boy
drowned in Los Angeles and the police couldn't find him. However, the boy
turned up in the pool a couple of days later. The police claim that the pool was dirty and
when they looked in the pool, it looked like they were looking at the bottom when in fact, they
really couldn't see the bottom where the boy was. How does this
work?
Answer:
Water is transparent and that is why you can see
through it. Light passing through water is absorbed slightly but a much more important thing
is the scattering of the light as it meets small particles (even down to molecular size) in the
water. If the water is dirty not much light will reach the bottom of the pond. Therefore not
much light will be reflected back and there might well be so little that whatever is on the
bottom of the pond will not be visible to someone looking in from above.