Question

With the help of a ray diagram show how a pencil appears when dipped in water.

Answer 1

Hint: The speed of light changes when light travels from one medium to another medium. In this example when light falls on the surface of the water either reflection, refraction may occur. We can observe this phenomenon in our day to day life.

Complete step by step answer:
If a pencil scale dipped in water as shown in the below figure it appears to be bent. But it's actually not broken, let's study the case why it appears to be bent.

When light falls on water or any other surface there must be reflection, refraction, and absorption occur. Absorption happens with very less amount, so we can neglect it.
When light travels from one medium to another, that light bounces back to the same medium as reflection.
In other cases light travels from one medium to another, light will bend at the surface of interference this phenomenon known as refraction.
In this case light travels from air medium to water medium there must be change in speed of light as it enters another medium. Here, the speed of light is more in the air medium when it enters the water medium where speed of light is decreased. That’s why there is a bending of light, this bending of light occurs at the interference of the two mediums or we can say this phenomena occurs whenever there will be change in medium.

Hence, when a pencil dipped in water it looks bent at the interference of the air and water medium.

Note: This question may ask with a changing medium instead of water. There we can consider mass density and optical density. The optical density term is related to only the speed of light. In this experiment the refraction process occurs.