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 session. Visit 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
Short Answer Type :
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:
- 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.
- 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.
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