Concepts of Physics

IIT JEE Physics (1978-2018: 41 Years) Topic-wise Complete Solutions

To get image from plane mirrors with no lateral inversion

Objective

To get image from plane mirrors with no lateral inversion.

Introduction

When image is formed in a plane mirror, it is laterally inverted. Our mind is trained to recognize this lateral inversion and hence we have no problem in combing our hair or adjusting our ear rings. However, if you use a pair of mirrors and see the image after two reflections, the lateral inversion will go away. You can design several interesting activities using this fact.

Apparatus

Two plane mirrors joined together with arrangement to place them vertically at an angle, a cap with colored strips marked.

Procedure

  1. Place the two mirrors vertically in the same plane (\(\theta=180\, \mathrm{degree}\)) and at a height where you can see the image of your face.
  2. Tilt the mirror to reduce the angle between them till you start seeing image of boundary of one mirror into the other. Position your head so that you see your image in each of the mirrors.
  3. Ask your friend to stand in this position looking at his/her image.
  4. Put the cap on the friend’s head.
  5. Now starts the game. You will be calling the colour and the friend has to touch that colour in one go. Call `red’ and see if your friend is able to touch red in one go. Similarly do for more colours.
  6. Put a strip of paper with some words written on it. Look at the image in any of the mirrors. How does it look like?

Question: Draw a ray diagram to explain the above findings.