A pencil when dipped in water in a glass tumbler appears to be bent at the interface of air and water. Will the pencil appears to be bent to the same extent, if instead of water we use liquids like, kerosene or turpentine. Support your answer with reason.

AcademicPhysicsNCERTClass 10

No, This depends on the refractive index of the liquid in which the pencil is dipped.

A pencil partly immersed in water appears to be bent at the water surface because of the refraction of light which takes place when light rays pass from the tank of water into the air. 

In the figure given below, the portion BO of the pencil AO is immersed in water and it appears to be bent at point B. A ray of light OC coming from the lower end O of the pencil passes from water to air and gets refracted away from the normal in the direction CX. Another ray OD gets refracted along with in the direction DY. The two refracted rays, CX and DY, when produced backward, appear to meet at a point I. And, the point I is nearer to the water surface than point O. Thus, a virtual image of the end O of the pencil is formed as point I. So, the human eye at position E sees the end O of the pencil at I, so the pencil appears to be bent.

Updated on 10-Oct-2022 13:27:44