A pencil when dipped in water in

Question:

A pencil when dipped in water in a glass tumbler appears to be bent at the interface of air and water. Will the pencil appear to be bent to the same

extent, if instead of water, we use liquids like, kerosene or turpentine. Support your answer with reason.

Solution:

A pencil dipped in water appears to be bent at the interface of air and water due to the refraction of light. The refraction of light occurs because the

speed of light changes when light travels from one medium to another. The pencil will not appear to be bent to the same extent, when it is dipped

in kerosene or turpentine. This is because refractive index of kerosene or turpentine is greater than the index of water and hence speed of light (v

= c/n) is less in kerosene or turpentine as compared to in water.

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