Question

The diagram shows straw partially immersed in water in the glasses.

1. Why does the straw in water appear thicker as compared to the straw outside water?
2. Why does the straw appear discontinuous in water?

Answer 1

1. The curved glass and water refract light from the submerged part of the straw. They act somewhat like a convex lens, making that part appear enlarged and therefore thicker.
2. Light from the part under water bends as it passes from water into air. The submerged part consequently appears raised and shifted from its actual position. It does not line up with the part outside the water, so the straw appears bent or discontinuous.