Question

A man 1 m tall steps into a stream which looks 90 cm deep. He finds himself completely submerged in water from head to toe. He was tricked! How did that happen?

Answer 1

It happened because of the refraction of light rays that pass from the stream to air. When a man looks into a stream, it appears to be less deep than it really is. Therefore, when a 1 m (100 cm) tall man steps into a stream that looks 90 cm deep, he finds himself completely submerged.