Question

A boy 1m tall looks at the swimming pool, which appears to be 75 cm deep, according to the people around him. He finds himself almost completely submerged in water when he steps into the water. Was he tricked? How did it happen?

Answer 1

When you look vertically downwards into a swimming pool full of water the bottom of the pool seems closer to you than it really is. The apparent depth at this point can be worked out using the formula:

Apparent depth = Real depth/Refractive index of water

However as you look towards the end of the pool the bottom seems to curve upwards – we are thinking about a pool of constant depth to start with.


If the depth of the pool really does change then the situation becomes more complex and you would need to allow for that when drawing the diagram