Question

A swimming pool appears shallower than its actual depth due to

• A. Dispersion
• B. Reflection
• C. Refraction
• D. Scattering

Answer 1

Answer: (C)

Refraction of light at the surface of the water makes swimming pools appear shallower than its actual depth when viewed from directly above.

The reason is that the rays of light reaching us from the object at the bottom of the water do not come straight to us. The light travels straight as long as it is in the water, but if it emerges obliquely from the water into the air it is bent downward toward the surface. This bending is known as refraction, and it occurs whenever light passes from one transparent medium into another of different density.Our eyes do not take refraction into account but judge the position of the object as if the light came in a straight line.

When light emerges from glass or water into the air it speeds up again. If it meets the glass-air boundary at any angle other than 0o it will refract away from the normal. This is true for small angles – something else happens when the angles get larger.

So, swimming pools appear to get shallower as you look towards the end furthest from you.