Page 145 - Physics_Form_2

Nature and reflection of light

mirror as the object is in front of the mirror, therefore, the new distance between the
object and its image will be:

distance between object and image  2  distance of object from mirror 

 2 1 cm   2 cm
FOR ONLINE READING ONLY
Therefore, the new distance between the object and its image is 2 cm.

Example 4.2
N E P R E C T
Two plane mirrors are placed O P X V R T U
at an angle of 60° to each
other. When an object is placed R L V I R T U
between them, find the number M A L R E A L
of images formed due to repeated A N I T C A R
reflections. L E O U T A E

Solution A I M A G E J
N K N L E N C
Given θ = 60 !

Substitute into the formula 2. The distances and heights of an object
placed in front of a plane mirror are
360 !
n = −1 provided in columns A and B, respectively.
θ In columns C and D, the distances and

360 ! 360 ! heights of the image are listed, but not in
n = −1= n = −1 the correct order. Correct the order.
θ 60 !
n  61 5 Column Column Column Column
A B C D
Therefore, 5 images are formed 10 cm 5 cm 5 cm 10 cm
due to repeated reflections.
5 cm 10 cm 10 cm 8 cm
6 cm 8 cm 6 cm 5 cm

Exercise 4.2
3. An object is placed in front of a plane
1. Some letters are provided in mirror. The mirror is moved away from
the following boxes. Create the object at a speed of 0.25ms . What
−1
meaningful words related is the speed of the image with respect to
to the reflection of light by the mirror and to the object?
selecting the horizontal and 4. A ray of light strikes a plane mirror such
vertical sequences. that the angle with the mirror is 20°. What

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Physics Form 2 Final.indd 139 25/10/2025 10:27