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Question
A straight stick partly dipped in water obliquely, appears to be bent at the surface of water.
Solution 1
The phenomenon is due to refraction of light.
A ray of light OC coming from O passes from water into air and gets refracted away from normal (along CX). Another ray OD gets refracted along DY. The two refracted rays CX and DY, when produced backwards, appear to meet at the point I. Thus, I is the virtual image of the end O of the stick. So, the stick appears to be bent as shown below.
Solution 2
- Light Refraction: When light passes from one medium (e.g., water) to another (e.g., air), it changes speed and direction. Light rays traveling from the submerged part of the stick (in water) to the observer’s eyes (in air) bend away from the normal at the water's surface.
- Apparent Bending: Due to this bending of light, the part of the stick underwater appears shifted upward. As a result, the stick seems bent at the surface of the water, even though it is straight.
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