Selina solutions concise physics class 9 icse Solutions for Chapter 7 chapter 7 reflection of light

Exercises in Chapter 7 chapter 7 reflection of light Grade 9

Exercise 7A

Exercise 7B

Exercise 7C

Questions in Exercise 7A

What do you mean by reflection of light?

State which surface of the plane mirror reflects most of the light incident on it: the front smooth surface or the back silvered surface

Explain the following terms:

(a) Plane mirror

(b) Incident ray

(c) Reflected ray

(d) Angle of incidence and

(e) Angle of reflection

With the help of diagrams, explain the difference between regular and irregular reflection

Differentiate between the reflection of light from a plane mirror and that from a plain sheet of paper.

State the two laws of reflection of light

State the laws of reflection and describe an experiment to verify them.

A light ray is incident normally on a plane mirror.

(a) What is its angle of incidence?

(b) What is the direction of the reflected ray? Show it on a diagram

Draw a diagram to show the reflection of a ray of light by a plane mirror. In the diagram, label the incident ray, the reflected ray, the normal, the angle of incidence, and the angle of reflection.

The figure shows an incident ray AO and the normal ON on a plane mirror. The angle which the incident ray AO makes with the mirror is 30°.

(a)Find the angle of incidence.

(b)Draw the reflected ray and then find the angle between the incident and reflected rays.

The diagram shows a point object P in front of a plane mirror MM1.

(a) Complete the diagram by taking two rays from point P to show the formation of its image.

(b) In the diagram, mark the position of the eye to see the image.

(c) Is the image formed real or virtual? Explain why

The diagram below shows an object XY in front of a plane mirror MM1. Draw the diagram, path of two rays from each point X and Y of the object to show the formation of its image

(a) Write three characteristics of the image formed by a plane mirror?

(b) How is the position of the image related to the position of the object

Differentiate between a real and a virtual image

What is meant by a lateral inversion of an image in a plane mirror? Explain it with the help of a ray diagram

The letters on the front of an ambulance are written laterally inverted like ƎƆИA⅃UꓭMA.

Give reason.

Why is it difficult to read the image of the text of a page formed due to reflection by a plane mirror?

According to the law of reflection :

(a) i/r = Constant

(b) sin i/sin r = Constant

(c) i + r = Constant

(d) i = r

The image formed by a plane mirror is :

(a) Erect and diminished

(b) Erect and enlarged

(c) Inverted and of the same size

(d) Erect and of the same size

The image formed by a plane mirror is :

(a) Real

(b) Virtual

(c) Virtual with lateral inversion

(d) Real with lateral inversion

A ray is an incident on a plane mirror. Its reflected ray is perpendicular to the incident ray.

Find the angle of incidence

A man standing in front of a plane mirror finds his image at a distance 6 metre from himself. What is the distance of a man from the mirror

An insect is sitting in front of a plane mirror at a distance 1 m from it.

(a)Where is the image of the insect formed?

(b) What is the distance between the insect and its image?

An object is kept at 60 cm in front of a plane mirror. If the mirror is now moved by 25 cm away from the object, how does the image shift from its previous position?

An optician while testing the eyes of a patient keeps a chart of letters 3 m behind the patient and asks him to see the letters on the image of the chart formed in a plane mirror kept at a distance 2 m in front of him. At what distance is the chart seen by the patient?

Questions in Exercise 7B

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

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

How many images are formed for a point object kept in between the two plane mirrors at right angles to each other? Show them by drawing a ray diagram.

Two plane mirrors are arranged parallel and facing each other at some separation. How many images are formed for a point object kept in between them? Show the formation of

images with the help of a ray diagram

State two uses of a plane mirror

Two plane mirrors are placed making an angle of 60° in between them. For an object placed in between the mirrors, the number of images formed will be :

(a) 3

(b) 6

(c) 5

(d) Infinite

In a barber’s shop, two plane mirrors are placed:

(a) Perpendicular to each other

(b) Parallel to each other

(c) At an angle of 60° between them

(d) At an angle of 45° between them

State the number of images of an object placed between the two plane mirrors, formed in each case when the mirrors are inclined to each other at

(a) 90° and

(b) 60°

An object is placed

(i) asymmetrically

(ii) symmetrically, between two plane mirrors inclined at an angle of 50°. Find the number of images formed

Questions in Exercise 7C

What is a spherical mirror?

Name the two kinds of spherical mirrors and distinguish between them

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

Draw suitable diagrams to illustrate the action of

(i) concave mirror, and

(ii) convex mirror,

on a beam of light, incident parallel to the principal axis.

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.

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

Explain the meaning of the terms focus and focal length in case of a convex mirror, with the help of a suitable ray diagram

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

i) Name the mirrors shown in figure (a) and (b).

(ii)In each case (a) and (b), draw the reflected rays for the given incident rays and mark focus

by the symbol F.

Complete the following diagrams in the figure by drawing the reflected rays for the incident rays

1 and 2.

State the two consecutive rays that are chosen to construct the image by a spherical mirror for a given object? Explain your answer with the help of suitable ray diagrams

The figure shows a concave mirror with its pole at P, focus F, and center of curvature C. Draw ray diagram to show the formation of the image of an object OA

Figure shows a concave mirror with its pole at P, focus F and center of curvature C. Draw ray diagram to show the formation of image of an object OA.

The diagram below in figure shows a convex mirror. C is its center of curvature and F is its focus. (i) Draw two rays from A and hence locate the position of image of object OA. Label the image IB.(ii) State three characteristics of the image

Draw a ray diagram to show the formation of image by a concave mirror for an object placed between its pole and focus. State three characteristics of the image

Draw a ray diagram to show the formation of an image by a concave mirror for an object beyond its center of curvature. State three characteristics of the image.

Draw a ray diagram to show the formation of the image of an object kept in front of a convex mirror. State three characteristics of the image

Name the mirror which always produces an erect and virtual image. How is the size of the image related to the size of the object?

(a) For what position of object, the image formed by a concave mirror is magnified and erect?

(b) State whether the image in part (a) is real or virtual?

(a) State the position of the object for which the image formed by a concave mirror is of the same size

(b) Write two more characteristics of the image

(a) What is a real image?

(b) What type of mirror can be used to obtain a real image of an object?

(c) Does the mirror mentioned in part (b) form real image for all locations of the object?

Discuss the position and nature of the image formed by a concave mirror when an object is moved from infinity towards the pole of the mirror

Discuss the position and nature of the image formed by a convex mirror when an object is moved from infinity towards the pole of mirror

Name the kind of mirror used to obtain:

(a) A real and enlarged image,

(b) A virtual and enlarged image,

(c) A virtual and diminished image,

(d) A real and diminished image

How is the focal length of a spherical mirror related to its radius of curvature

Write the spherical mirror’s formula and explain the meaning of each symbol used in it.

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

Up to what maximum distance from the pole the image in a convex mirror can be obtained?

What will be the location of the object then?

Up to what maximum distance from a concave mirror, the image can be obtained? What will be the location of the object for it?

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

State two uses of a concave mirror

State the kind of mirror used

(a) By a dentist

(b) As a search- light reflector

(a) When a concave mirror is used as a shaving mirror, where is the person’s face in relation to the focus of the mirror?

(b) State three characteristics of the image seen in part (a)

Which mirror will you prefer to use as a rear view mirror in a car: plane mirror or convex mirror? Give one reason

Why does a driver use a convex mirror instead of a plane mirror as a rearview mirror? Illustrate your answer with the help of a ray diagram.

For an incident ray directed towards the center of curvature of a spherical mirror, the

reflected ray:

(a) Retraces its path

(b) Passes through the focus

(c) Passes through the pole

(d) Becomes parallel to the principal axis

The image formed by a convex mirror is:

(a) Erect and diminished

(b) Erect and enlarged

(c) Inverted and diminished

(d) Inverted and enlarged

A real and enlarged image can be obtained by using a:

(a) Convex mirror

(b) Plane mirror

(c) Concave mirror

(d) Either convex

The radius of curvature of a convex mirror is 40cm. find its focal length

The focal length of a concave mirror is 10cm. find its radius of curvature.

An object of height 2cm is placed at a distance 20cm in front of a concave mirror of focal length 12cm. Find the position, size, and nature of the image

An object is placed at a 4cm distance in front of a concave mirror of radius of curvature 24cm. Find the position of the image. Is the image magnified

At what distance from a concave mirror of focal length 25cm should an object be placed so that the size of the image is equal to the size of the object. Draw a ray diagram to show this.

An object 5cm high is placed at a distance 60cm in front of a concave mirror of focal length 10cm. Find (i) the position and (ii) size, of the image

A point light source is kept in front of a convex mirror at a distance of 40cm. The focal length of the mirror is 40cm. Find the position of the image.

When an object of height 1cm is kept at a distance 4cm from a concave mirror, its erect image of height 1.5cm is formed at a distance 6cm behind the mirror. Find the focal length of the mirror

An object of length 4cm is placed in front of a concave mirror at a distance 30cm. The focal length of the mirror is 15cm. (a) where will the image form? (b) What will be the length of

image?

A concave mirror forms a real image of an object placed in front of it at a distance 30cm, of size three times the size of the object. Find (a) the focal length of the mirror (b)

A concave mirror forms a virtual image of size twice that of the object placed at a distance5cm from it. Find: (a) the focal length of the mirror (b) position of the image.

The image formed by a convex mirror is of size one-third the size of the object. How are u and v related?

The erect image formed by a concave mirror is of size double the size of the object. How are u and v related?

The magnification for a mirror is -3. How are u and v related