Final answer:
When a person wades in a pool, their legs appear very short due to the phenomenon of refraction. Light rays from the submerged legs change direction as they pass from water to air, creating an apparent distance between the feet and the observer's eye.
Step-by-step explanation:
When a person wades in a pool, their legs appear very short due to the phenomenon of refraction. Refraction occurs when light waves pass from one medium to another with a different refractive index, causing the light to change direction. In this case, the light rays from the legs pass from water, which has a higher refractive index than air, to the air. As a result, the light rays bend away from the normal and the legs appear shorter than they actually are.
To better understand this, we can use a ray diagram. Imagine an observer standing outside the water looking at a person's legs submerged in the pool. The light rays from the submerged legs travel from the feet to the observer's eye. As the rays pass from water to air, they bend away from the normal, creating an apparent distance between the feet and the observer's eye. This apparent distance is what makes the legs appear shorter.