解释水如何使光弯折

Explain how water behaves like a lens?

Why does the water magnify images?

The Science Behind the Science
The speed of light in a vacuum is constant (300 million meters per second) but the speed of light is less than this value when light travels through denser media such as air, water, plastic and glass. Lenses change the direction of light based on the principle of refraction, where light will change direction in relation to how its speed changes when moving from one transparent medium to another. Lenses are found in telescopes, microscopes, the human eye, spectacles, cameras and projectors.

A common material that behaves like a lens is water. For example, a straight straw placed in a glass of water will look different above the water compared to below the water when viewed from the side, making the straw look distorted or bent. This happens because light reflected from the top part of the straw (above the water) travels straight through the air to our eyes whereas light reflected from the bottom part of the straw (below the water) is refracted as it moves from the water to the air, causing the image of the straw to be in a slightly different place.