# Reflection of Light Exe-7B Short Answer Concise Physics ICSE Class-9 Selina Publishers

Reflection of Light Exe-7B Short Answer Concise Physics ICSE Class-9 Selina Publishers. There is the solutions of Short Answer type Questions of your latest textbook which is applicable in 2024-25 academic sessionVisit official Website CISCE for detail information about ICSE Board Class-9.

## Reflection of Light Exe-7B Short Answer Type

Concise Physics ICSE Class-9 Selina Publishers

 Board ICSE Class 9 Subject Physics Writer / Publication Concise Selina Publishers Chapter-7 Reflection of Light Exe-7B Images Formed by a pair of Mirrors Topics Solution of Exe-7(B)  Short Answer Type Academic Session 2024-2025

### Exercise- 7B Images Formed by a pair of Mirrors

page -174

##### Q1- Two plane mirrors are placed making an angle θ in between them. Write an expression for the number of images formed of an object placed in between the mirrors. State the condition, if any.

Ans- If two mirrors make an angle  with each other and object is placed in between the two mirrors, the number of images formed is n or (n – 1) depending upon n = 360o / o is odd or even.(a) If n = 360o / o is odd,

(i) The number of images formed is n, when the object is placed asymmetrically between the mirrors.

(ii) The number of images formed is n-1, when the object is placed symmetrically between the mirrors.

(b) If n = 360o / o is even, the number of images is always n-1.

##### Q2- Two plane mirrors are placed making an angle θ° in between them. For an object placed in between the mirrors, if angle is gradually increased from 0° to 180°, how will the number of images change : increase, decrease or remain unchanged?

Ans- The number of images formed is given as n = θ 360 θSo, if q is gradually increased, n decreases.

##### Q3- State two uses of a plane mirror.

Ans- Two uses of plane mirror:

1. In barber’s shop for seeing the hairs at the back of head, two mirrors facing each other are fixed on opposite walls at the front and back of the viewer.
2. In solar heating devices such as a solar cooker, solar water heater, etc., a plane mirror is used to reflect the incident light rays from sun on the substance to be heated.

— : end of Reflection of Light Exe-7B Short Answer Concise Physics ICSE Class-9 Selina Publishers. :—

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