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

Reflection of Light Exe-7C 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.

distinguish between a plane mirror, a concave mirror and a convex mirror, without touching them

Reflection of Light Exe-7C 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-7C Spherical Mirrors
Topics Solution of Exe-7(C) Short Answer Type
Academic Session 2024-2025


Exercise- 7C Spherical Mirrors

page -189

Short Answer Type :

Q1- Name the two kinds of spherical mirrors and distinguish between them.

Ans- Two kind of spherical mirrors are concave and convex. Distinction between concave and convex mirror: A concave mirror’s bulging surface is silvered and reflection takes place from the hollow surface but a convex mirror’s inner surface is silvered and reflection takes place from the  bulging surface.

Q2- Define the terms pole, principal axis and centre of curvature with reference to a spherical mirror. 

Ans- Pole: The geometric centre of the spherical surface of mirror is called the pole of mirror.
Principal axis: It is the straight line joining the pole of the mirror to its centre of curvature.
Centre of curvature: The centre of curvature of a mirror is the centre of the sphere of which the mirror is a part.

Q3- Name the spherical mirror which (i) diverges (ii) converges the beam of light incident on it. Justify your answer by drawing a ray diagram in each case.

Ans- (i) Convex mirror diverges a beam of light falling on it.

 Name the spherical mirror which (i) diverges

(ii) Concave mirror converges a beam of light falling on it.

(ii) Concave mirror converges a beam of light falling on it.

Q4- Define the terms focus and focal length of a concave mirror. Draw diagram to illustrate your answer.

Ans- Focus of a concave mirror: The focus of a concave mirror is a point on the principal axis through which the light rays incident parallel to principal axis, pass after reflection from the mirror.

Focal length of a concave mirror: The distance of the focus from the pole of the concave mirror is called its focal length.

Define the terms focus and focal length of a concave mirror. Draw diagram to illustrate your answer.

Q5- State the direction of incident ray which after reflection from a spherical mirror retraces its path. Give a reason to your answer.

Ans- Incident ray is directed towards the centre of curvature because the ray is normal to the spherical mirror, so <i = <= 0.

Q6- What is meant by magnification ? Write its expression. What is its sign for the
(a) real (b) virtual, image?

Ans- Magnification is the ratio of the length of image to the length of the object
m = -v/u Where, u and v is the object and image distance, respectively.

Hence, we have

  1. For real image: u and v are negative. So, m is negative.
  2. For virtual image: u is negative and v is positive. So, m is positive
Q7- Upto what maximum distance from the pole, the image in a convex mirror can be obtained ? What will be the location of object then ?

Ans- The maximum  distance from the pole , at which the image in a convex mirror can be obtained is the focal length , as the image formed of an object by a concave mirror is always between pole and the focus . The object would be located at infinity then.

Q8- Upto what maximum distance from a concave mirror, the image in a convex mirror can be obtained ? What will be the location of object then?

Ans- The maximum distance that can be obtained in concave mirror is infinity. For this case the object has to be at focus.

Q9- How will you distinguish between a plane mirror, a concave mirror and a convex mirror, without touching them?

Ans- To distinguish between a plane mirror, concave mirror and convex mirror, the given mirror is held near the face and image is seen. There can be following three cases:

Case (i): If the image is upright, of same size and it does not change in size by moving the mirror towards or away from the face, the mirror is plane.

(ii) If the image is upright and magnified, and increases in size on moving the mirror away, the mirror is concave.

(iii) If the image is upright and diminished and decreases in size on moving the mirror away, the mirror is convex

Q10- State two uses of a concave mirror.

Ans- Two uses of concave mirror:

(i) It is used as a shaving mirror.

(ii) It is used as reflector in torch, head light of automobiles etc.

Q11- (a) When a concave mirror is used as a shaving mirror, where is the person’s face in relation to the focus of mirror?
(b) State three characteristics of the image seen in part (a).

Ans- (a) The person’s face is between the pole and focus of the mirror.(b) The image formed is erect, virtual and magnified.

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

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