NIOS Class 10 Science Activity 15.3 Light Energy

In this activity, we will study how the angle of an object with the horizontal changes when its image is formed by a plane mirror kept at different angles.

Light Energy Activity

This activity is based on the NIOS Class 10 science and technology (212) Chapter 15- Light Energy, Module 4.

Relation Between Object and Mirror Angle

Aim

To find the relation between the angle of a plane mirror and the angle of the object

Materials Required

   1.  Plane mirror

   2. Protractor

   3. Pencil or linear object

   4. Paper and scale

Procedure

We place a plane mirror on a table at an angle of 30º with the horizontal line, and then we place a straight object in front of the mirror such that its image appears straight in the mirror.

 We note down the angle made by the object with the horizontal line. Now we repeat the activity for different mirror angles: 45º,60º, and 90º.

Observation

 We record all the observations in the table as follows:

Angle of mirror(α)	Angle of object(θ)
30º	60º
45º	45º
60º	30º
90º	0º

 

Explanation

The image formed is always straight for all angles.  The condition for the image to appear straight is

  θ+ α=90°

So, the sum of the angle of the object with the horizontal and the angle of the mirror with the horizontal must always be 90º.

Conclusion

 We can conclude that the image of an object appears straight when

Angle of object = 90º - Angle of mirror

The position of the object depends directly on the angle of the mirror.