Question

Why do we observe that when a stick is kept in water then it appears to bend under water?
A) Light bends while travelling from one medium to another
B) Light doesn't bend while travelling from one medium to another
C) Light move upward while travelling from one medium to another
D) Light move downward while travelling from one medium to another

Answer 1

Hint : The bending of light (as well as sound, water, and other waves) when it flows from one transparent medium into another is known as refraction. Lenses, magnifying glasses, prisms, and rainbows are all conceivable because of this bending through refraction. Even our eyes are reliant on light bending.

Complete Step By Step Answer:
The propagation of light, as we all know, requires a medium. Every media has a refractive index, which is commonly measured in comparison to air. The refractive index of air is assumed to be unity for the purpose of simplicity. When we view anything, the light from it passes through the medium of air until it reaches our retina. During its propagation, light has a defined wavelength and speed. When an item is positioned between two mediums, light passes through both media before reaching our eyes. The two mediums are air and water in this case. Refraction occurs because water has a greater refractive index than air. The speed of light slows down when the medium changes. Because of the refraction, the speed of light appears to be different, and the stick in the water seems twisted or broken. The human eye, like optical prisms and lenses, uses refraction to redirect light. The refractive index of materials changes in proportion to the wavelength of light, and hence the angle of refraction changes as well. Prisms and rainbows divide white light into its constituent spectrum colours due to this phenomenon known as dispersion.
Hence option A is correct.

Note :
Due to refraction of light, the stick appears twisted when put in a glass tumbler with water. When light moves from one medium to another, its speed varies, which is known as refraction. The bending is not the same when the stick is dipped in kerosene or oil since they are optically denser than water.