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# Lakhmir Singh solutions for Class 10 Science chapter 4 - Reflection of Light

## Chapter 4: Reflection of Light

#### Chapter 4: Reflection of Light solutions [Pages 173 - 175]

Q 1 | Page 173

What happens when a ray of light falls normally (or perpendiculary) on the surface of a plane mirror?

Q 2 | Page 173

A ray of light is incident on a plane mirror at an angle of 30°. What is the angle of reflection

Q 3 | Page 173

A ray of light strikes a plane mirror at an angle of 40° to the mirror surface. What will be the angle of reflection?

Q 4.1 | Page 173

A ray of light is incident normally on a plane mirror. What will be the

angle of incidence?

Q 4.2 | Page 173

A ray of light is incident normally on a plane mirror. What will be the

angle of reflection?

Q 5.1 | Page 173

What type of image is formed:

in a plane mirror?

Q 5.2 | Page 173

What type of image is formed:

on a cinema screen?

Q 6 | Page 173

What kind of mirror is required for obtaining a virtual image of the same size as the object?

Q 7 | Page 173

What is the name of the phenomenon in which the right side of an object appears to be the left side of the image in a plane mirror?

Q 8 | Page 173

Name the phenomenon responsible for the following effect:
When we sit in front of a plane mirror and write with our right hand, if appears in the mirror that we are writing with the left hand.

Q 9 | Page 173

If an object is placed at a distance of 10 cm in from of a plane mirror, how far would it be from its image?

Q 10 | Page 173

Which property of light makes a pencil cast a shadow when it is held in front of a light source?

Q 11 | Page 173

The image seen in a plane mirror cannot be formed on a screen. What name is given to this type of image?

Q 12 | Page 173

Fill in the following blank with a suitable word:
When light is reflected, the angles of incidence and reflection are ............ .

Q 13 | Page 173

State whether the following statement is true of false:
A student says that we can see an object because light from our eyes is reflected back by the object.

Q 14 | Page 173

Where is the image when you look at something in a mirror?

Q 15 | Page 173

A ray of light strikes a plane mirror such that its angle of incidence is 30°. What angle does the reflected ray make with the mirror surface?

Q 16 | Page 173

What is the difference between a real image and a virtual image? Give one example of each type of image

Q 17.1 | Page 173

The letter F is placed in front of a plane mirror:

How would its image look like when seen in a plane mirror?

Q 17.2 | Page 173

The letter F is placed in front of a plane mirror:

What is the name of the phenomenon involved?

Q 18 | Page 173

What is lateral inversion? Explain by giving a suitable example.

Q 19 | Page 173

Write the word AMBULANCE as it would appear when reflected in a plane mirror. Why is it sometimes written in this way (as its mirror image) on the front of an ambulance?

Q 20 | Page 173

What are the important differences between looking at a photograph of your face and looking at yourself in a plane mirror?

Q 21.1 | Page 173

A wall reflects light and a mirror also reflects light. What difference is three in the way they reflect light?

Q 21.2 | Page 173

Which type of reflection of light leads to the formation of images?

Q 22.1 | Page 174

What is the difference between regular reflection of light and diffuse reflection of light?

Q 22.2 | Page 174

What type of reflection of light takes place from:

(a) a cinema screen
(b) a plane mirror
(c) a cardboard
(d) still water surface of a lake

Q 23 | Page 174

What can  you see in a completely dark room? If you switch on an electric bulb in this dark room as a light source, explain how you could now see:
(a) the electric bulb
(b) a piece of white paper.

Q 24.1 | Page 174

A boy with a mouth 5 cm wide stands 2 m away from a plane mirror. Where is his image and how wide is the image of his mouth?

Q 24.2 | Page 174

The boy walks towards the mirror at a speed of 1 m/s. At what speed does his image approach him?

Q 25.1 | Page 174

An extended object in the form of an arrow pointing upward has been placed in front of a plane mirror. Draw a labelled ray-diagram to show the formation of its image.

Q 25.2 | Page 174

State the uses of plane mirrors.

Q 26.1 | Page 174

What is meant by 'reflection of light'?

Q 26.2 | Page 174

Define the following terms used in the study of reflection of light by drawing a labelled ray-diagram:

(a) Incident ray
(b) Point of incidence
(c) Normal
(d) Reflected ray
(e) Angle of incidence
(f) Angle of reflection

Q 27 | Page 174

State and explain the laws of reflection of light at a plane surface (like a plane mirror), With the help of a labelled ray-diagram. Mark the angles of 'incidence' and 'reflection' clearly on the diagram. If the angle of reflection is 47.5°, what will be the angle of incidence?

Q 28 | Page 174

With the help of a labelled ray-diagram, describe how a plane mirror forms an image of a point source of light placed in front of it. State the characteristics of the image formed in a plane mirror.

Q 29.1 | Page 174

Explain why, though both a plane mirror and a sheet of paper reflect light but we can see the image of our face in a plane mirror but not in a sheet of paper.

Q 29.2 | Page 174

The image in a plane mirror is virtual and laterally inverted. What does this statement mean?

Q 29.3 | Page 174

Write all the capital letters of the alphabet which look the same in a plane mirror.

Q 30 | Page 174

The angle of reflection is equal to the angle of incidence:

(a) always
(b) sometimes
(c) under special conditions
(d) never

Q 31 | Page 174

The angle between an incident ray and the plane mirror is 30°. The total angle between the incident ray and reflected ray will be:

(a) 30°
(b) 60°
(c) 90°
(d) 120°

Q 32 | Page 174

A ray of light is incident on a plane mirror making an angle of 90° with the mirror surface. The angle of reflection for this ray of light will be:

(a) 45°
(b) 90°
(c) 0°
(d) 60°

Q 33 | Page 174

The image of an object formed by a plane mirror is:

(a) virtual
(b) real
(c) diminished
(d) upside-down

Q 34 | Page 174

The image formed by a plane mirror is :

(a) virtual, behind the mirror and enlarged.
(b) virtual, behind the mirror and of the same size as the object.
(c) real, at the surface of the mirror and enlarged.
(d) real, behind the mirror and of the same size as the object.

Q 35 | Page 174

The figure given alongside shows the image of a clock as seen a plane mirror. The correct time is:
Figure

(a) 2.25
(b) 2.35
(c) 6.45
(d) 9.25

Q 36 | Page 174

A man stands 10 m in front of a large plane mirror. How far must the walk before he is 5 m away from his image?

Q 37 | Page 175

An object is placed 20 cm in front of a plane mirror. The mirror is moved 2 cm towards the object. The distance between the positions of the positions of the original and final images seen in the mirror is:

(a) 2 cm
(b) 4 cm
(c) 10 cm
(d) 22 cm

Q 38 | Page 175

A man sits in an optician's chair looking into  plane mirror which is 2 m away from him and views the image of a chart which faces the mirror and is 50 cm behind his head. How far away from his eyes does the chart appear to be?

Q 39 | Page 175

A ray of light strikes a plane mirror PQ at an angle of incidence of 30°, is reflected from the plane mirror and then strikes a second plane mirror QR placed at right angles to the first mirror. The angle of reflection at the second mirror is:

(a) 30°
(b) 45°
(c) 60°
(d) 90°

Q 40 | Page 175

Explain how to read the following message which was found on some blotting paper:

#### Chapter 4: Reflection of Light solutions [Pages 178 - 179]

Q 1 | Page 178

Name the spherical mirror which has:

(a) virtual principal focus.
(b) real principal focus.

Q 2 | Page 178

Out of convex mirror and concave mirror, whose focus is situated behind the mirror?

Q 3 | Page 178

Find the focal length of a concave mirror whose radius of curvature is 32 cm.

Q 4 | Page 178

If the focal length of a convex mirror is 25 cm, what is its radius of curvature?

Q 5.1 | Page 179

Fill in the following blank with suitable word:

Parallel rays of light are reflected by a concave mirror to a point called the ..........

Q 5.2 | Page 179

Fill in the following blank with suitable word:

The focal length of a concave mirror is the distance from the ......... to the mirror.

Q 5.3 | Page 179

Fill in the following blank with suitable word:

A concave mirror .......... rays of light whereas convex mirror ............ rays

Q 5.4 | Page 179

ill in the following blank with suitable word:

For a convex mirror, parallel rays of light appear to diverge from a point called the ......... .

Q 6 | Page 179

What is a spherical mirror? Distinguish between a concave mirror and a convex mirror.

Q 7.1 | Page 179

Name the two types of spherical mirrors. What type of mirror is represented by the:

back side of a shining steel spoon?

Q 7.2 | Page 179

Name the two types of spherical mirrors. What type of mirror is represented by the:

front side of a shining steel spoon?

Q 8 | Page 179

What is the relation between the focal length and radius of curvature of a spherical mirror (concave mirror of convex mirror)? Calculate the focal length of a spherical mirror whose radius of curvature is 25 cm.

Q 9 | Page 179

Explain with a suitable diagram, how a concave mirror converges a parallel beam of light rays. Mark clearly the pole, focus and centre of curvature of concave mirror in this diagram.

Q 10 | Page 179

Describe with a suitable diagram, how a convex mirror diverges a parallel beam of light rays. Mark clearly the pole, focus and centre of curvature of concave mirror in this diagram.

Q 11 | Page 179

Define (a) centre of curvature (b) radius of curvature (c) pole (d) principal axis, and (e) aperture, of a spherical mirror with the help of a labelled diagram

Q 12.1 | Page 179

Define (i) principal focus of a concave mirror, and (ii) focal length of a concave mirror.

Q 12.2 | Page 179

Draw diagram to represent the action of a concave mirror on a beam of parallel light rays. Mark on this diagram principal axis, focus F, centre of curvature C, pole P and focal length f, of the concave mirror.

Q 13.1 | Page 179

What is meant by (i) principal focus of a convex mirror, and (ii) focal length of a convex mirror?

Q 13.2 | Page 179

Draw diagram to show the action of convex mirror on a beam of parallel light rays. Mark on this diagram principal axis, focus F, centre of curvature C, pole P and focal length f, of the convex mirror.

Q 14 | Page 179

In a convex spherical mirror, reflection of light takes place at:

(a) a flat surface
(b) a bent-in surface
(c) a bulging-our surface
(d) an uneven surface

Q 15 | Page 179

A diverging mirror is

(a) a plane mirror
(b) a convex mirror
(c) a concave mirror
(d) a shaving mirror

Q 16 | Page 179

If R is the radius of curvature of a spherical mirror and f is its focal length, then:

(aR = f
(bR = 2f
(c) R = f/2
(dR = 3f

Q 17 | Page 179

The focal length of a spherical mirror of radius of curvature 30 cm is:

(a) 10 cm
(b) 15 cm
(c) 20 cm
(d) 30 cm

Q 18 | Page 179

If the focal length of a spherical mirror is 12.5 cm, its radius of curvature will be:

(a) 25 cm
(b) 15 cm
(c) 20 cm
(d) 35 cm

Q 19 | Page 179

A communications satellite in orbit sends a parallel beam of signals down to earth. If these signals obey the same laws of reflection as light and are to be focussed onto a small receiving aerial, what should be the best shape of the metal 'dish' used to collect them?

Q 20.1 | Page 179

When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.

What is the nature of spherical mirror?

Q 20.2 | Page 179

When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.

Why is a hole burnt in the carbon paper?

Q 20.3 | Page 179

When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.

At which point of the spherical mirror the carbon paper is placed?

Q 20.4 | Page 179

When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.

What name is given to the distance between spherical mirror and carbon paper?

Q 20.5 | Page 179

When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.

What is the advantage of using a carbon paper rather than a white paper?

#### Chapter 4: Reflection of Light solutions [Pages 189 - 191]

Q 1 | Page 189

For what position of an object, a concave mirror forms a real image equal in size to the object?

Q 2 | Page 189

Where should an object be placed in front of the concave mirror so as to obtain its virtual, erect and magnified image?

Q 2.1 | Page 191

Which type of mirror has:

positive focal length?

Q 3 | Page 189

For which positions of the object does a concave mirror produce an inverted, magnified an real image?

Q 4 | Page 189

If an object is placed at the focus of a concave mirror, where is the image formed?

Q 5 | Page 189

If an object is at infinity (very large distance) in front of a concave mirror, where is the image formed?

Q 6 | Page 189

For what position of an object, a real and diminished image is formed by a concave mirror?

Q 7 | Page 189

Copy this figure in your answer book and show the direction of the light ray after reflection:

Q 8 | Page 189

Draw the following diagram in your answer book and show the formation of image of the object AB with the help of suitable rays:

Q 9 | Page 189

Draw the following diagram in your answer book and show the formation of image with the help of suitable rays:

Q 10 | Page 189

Which type of mirror could be used as a dentist's mirror?

Q 11 | Page 189

Which kind of mirror is used in the headlights of a car? Why is it used for this purpose?

Q 12 | Page 189

Explain why, a ray of light passing through the centre of curvature of a concave mirror gets reflected back along the same path.

Q 13 | Page 189

What is the minimum number of rays required for locating the image formed by a concave mirror for an object? Draw a ray diagram to show the formation of a virtual image by a concave mirror.

Q 14 | Page 189

With the help of a ray diagram, determine the position, nature and size of the image formed of an object placed at the centre of curvature of a concave mirror.

Q 15 | Page 189

Described with the help of a diagram, the nature, size and position of the image formed when an object is placed beyond the centre of curvature of a concave mirror.

Q 16 | Page 189

If an object is placed at a distance of 8 cm from a concave mirror of focal length 10 cm, discuss the nature of the image formed by drawing the ray diagram.

Q 17 | Page 189

Draw a ray diagram showing how a concave mirror can be used to produce a real, inverted and diminished image of an object.

Q 18 | Page 190

Which mirror is used as a torch reflector? Draw a labelled diagram to show how a torch reflector can be used to produce a parallel beam of light. Where is the bulb placed in relation to the torch reflector?

Q 19 | Page 190

State where an object must be placed so that the image formed by a concave mirror is:

(a) erect and virtual.
(b) at infinity.
(c) the same size as the object.

Q 20 | Page 190

With the help of a labelled ray diagram, describe how a converging mirror can be used to give an enlarged upright image of an object.

Q 21.1 | Page 190

Make labelled ray diagrams to illustrate the formation of:

a real image by a converging mirror.

Q 21.2 | Page 190

Make labelled  ray diagrams to illustrate the formation of:

a virtual image by a converging mirror.
Mark clearly the pole, focus, centre of curvature and position of object in each case.

Q 22 | Page 190

Briefly describe how you would find the focal length of a concave mirror quickly but approximately

Q 23 | Page 190

Which type of mirror is used in a solar furnace? Support your answer with reason.

Q 24 | Page 190

Name the type of mirror used by dentists. How does it help?

Q 25 | Page 190

Explain why, concave mirrors are used as shaving mirrors.

Q 26 | Page 190

Give two uses of concave mirrors. Explain why you would choose concave mirrors for these uses.

Q 27.1 | Page 190

Draw ray-diagrams to show the formation of images when the object is places in front of a concave mirror (converging mirror):

(i) between its pole and focus
(ii) between its centre of curvature and focus

Q 27.2 | Page 190

between its pole and focus

Describe the nature, size and position of the image formed in each case.

State one use of concave mirror bases on the formation of image as in case (i) above.

Q 28.1 | Page 190

Give two circumstances in which a concave mirror can form a magnified image of an object placed in front of it. Illustrate your answer by drawing labelled ray diagrams for both.

Q 28.2 | Page 190

Which one of these circumstances enables a concave mirror to be used as a shaving mirror?

Q 29 | Page 190

The real image formed by a concave mirror is larger than the object when object is:

(a) at a distance equal to radius of curvature
(b) at a distance less than the focal length
(c) between focus and centre of curvature
(d) at a distance greater than radius of curvature

Q 30 | Page 190

The real image formed by a concave mirror is smaller than the object if the object is:

(a) between centre of curvature and focus
(b) at a distance greater than radius of curvature
(c) at a distance equal to radius of curvature
(d) at a distance equal to focal length

Q 31 | Page 190

The image formed by a concave mirror is virtual, erect and magnified. The position of object is:

(a) at focus
(b) between focus and centre of curvature
(c) at pole
(d) between pole and focus

Q 32 | Page 190

The image formed by a concave mirror is real, inverted and of the same size as the object. The position of the object must then be:

(a) at the focus
(b) between the centre of curvature and focus
(c) at the centre of curvature
(d) beyond the centre of curvature

Q 33 | Page 190

The image formed by a concave mirror is real, inverted and highly diminished (much smaller than the object). The object  must be:

(a) between pole and focus
(b) at focus
(c) at the centre of curvature
(d) at infinity

Q 34 | Page 190

The angle of incidence for of light passing through the centre of curvature of a concave mirror is:

(a) 45°
(b) 90°
(c) 0°
(d) 180°

Q 35 | Page 191

In the concave reflector of a torch, the bulb is placed:

(a) between the pole and focus of reflector
(b) at the focus of reflector
(c) between focus and centre of curvature of reflector
(d) at the centre of curvature of reflector

Q 36 | Page 191

The focal length of a small concave mirror is 2.5 cm. In order to use this concave mirror as a dentist's mirror, the distance of tooth from the mirror should be:

(a) 2.5 cm
(b) 1.5 cm
(c) 4.5 cm
(d) 3.5 cm

Q 37 | Page 191

An object is 100 mm in front of a concave mirror which produces an upright (erect image). The radius of curvature of the mirror is:

(a) less than 100 mm
(b) between 100 mm and 200 mm
(c) exactly 200 mm
(d) more than 200 mm

Q 38 | Page 191

A virtual, erect and magnified image of an object is to be produced with a concave mirror of focal length 12 cm. Which of the following object distance should be chosen for this purpose?

(i) 10 cm
(ii) 15 cm
(iii) 20 cm

Q 39 | Page 191

A concave mirror has a focal length of 25 cm. At which of the following distance should a person hold his face from this concave mirror so that it may act as a shaving mirror?

(a) 45 cm
(b) 20 cm
(c) 25 cm
(d) 30 cm

Q 40 | Page 190

An object is placed at the following distances from a concave mirror of focal length 15 cm, turn by turn:

(a) 35 cm
(b) 30 cm
(c) 20 cm
(d) 10 cm
Which position of the object will produce:

(i) a magnified real image?
(ii) a magnified virtual image?
(iii) a diminished real image?
(iv) an image of same size as the object?

#### Chapter 4: Reflection of Light solutions [Pages 192 - 193]

Q 1 | Page 192

According to the "New Cartesian Singh Convention" for mirrors, what sign has been given to the focal length of:

a concave mirror?

Q 1.2 | Page 192

According to the "New Cartesian Singh Convention" for mirrors, what sign has been given to the focal length of:

a convex mirror?

Q 2.2 | Page 192

Which type of mirror has:

negative focal length?

Q 3 | Page 192

What is the nature of a mirror having a focal length of, +10 cm?

Q 4 | Page 192

What kind of mirror can have a focal length of, −20 cm?

Q 5 | Page 192

Complete the following sentence:

All the distances are measured from the .......... of a spherical mirror.

Q 6.1 | Page 192

What sign (+ve or −ve) has been given to the following on the basis of Cartesian Sigh Convention?

Height of a real image.

Q 6.2 | Page 192

What sign (+ve or −ve) has been given to the following on the basis of Cartesian Sigh Convention?

Height of a virtual image.

Q 7 | Page 192

Describe the New Cartesian Sigh Convention used in optics. Draw a labelled diagram to illustrate this sign convention.

Q 8 | Page 193

Giving reasons, state the 'signs' (positive or negative) which can be given to the following:

(a) object distance (u) for a concave mirror or convex mirror
(b) image distance (v) for a concave mirror
(c) image distance (v) for a convex mirror

Q 8 | Page 193

According to New Cartesian Sign Convention:

(a) focal length of concave mirror is positive and that of convex mirror is negative
(b) focal length of both concave and convex mirrors is positive
(c) focal length of both concave and convex mirrors is negative
(d) focal length of concave mirror is negative and that of convex mirror is positive

Q 9 | Page 193

According to New Cartesian Sign Convention:

(a) focal length of concave mirror is positive and that of convex mirror is negative
(b) focal length of both concave and convex mirrors is positive
(c) focal length of both concave and convex mirrors is negative
(d) focal length of concave mirror is negative and that of convex mirror is positive

Q 10 | Page 193

One of the following does not apply to a concave mirror this is:
(a) focal length is negative
(b) image distance can be positive or negative
(c) image distance is always positive
(d) height of image can be positive or negative

#### Chapter 4: Reflection of Light solutions [Pages 198 - 200]

Q 1 | Page 198

If the magnification of a body of size 1 m is 2, what is the size of the image?

Q 2 | Page 198

What is the position of the image when an object is placed at a distance of 20 cm from a concave mirror of focal length 20 cm?

Q 3.1 | Page 198

What is the nature of image formed by a concave mirror if the magnification produced by the mirror

+4

Q 3.2 | Page 198

What is the nature of image formed by a concave mirror if the magnification produced by the mirror

−2?

Q 4 | Page 198

State the relation between object distance, image distance and focal length of a spherical mirror (concave mirror or convex mirror).

Q 5 | Page 198

Write the mirror formula. Give the meaning of each symbol which occurs in it.

Q 6 | Page 198

What is the ratio of the height of an image to the height of an object known as?

Q 7 | Page 198

Define linear magnification produced by a mirror.

Q 8.1 | Page 198

Write down a formula for the magnification produced by a concave mirror.

in terms of height of object and height of image

Q 8.2 | Page 198

Write down a formula for the magnification produced by a concave mirror.

in terms of object distance and image distance

Q 10 | Page 198

Describe the nature of image formed when the object is placed at a distance of 20 cm from a concave mirror of focal length 10 cm

Q 10.1 | Page 198

Fill in the following blank with suitable word:

If the magnification has a plus sign, than image is ......... and.........

Q 10.2 | Page 198

Fill in the following blank with suitable word:

If the magnification has a minus sign, than the image is ......... and .......

Q 11.1 | Page 198

An object is placed at a distance of 10 cm from a concave mirror of focal length 20 cm.

Q 11.2 | Page 198

An object is placed at a distance of 10 cm from a concave mirror of focal length 20 cm.

Calculate the image distance.

Q 11.3 | Page 198

An object is placed at a distance of 10 cm from a concave mirror of focal length 20 cm.

State two characteristics of the image formed.

Q 12 | Page 198

If an object of 10 cm height is placed at a distance of 36 cm from a concave mirror of focal length 12 cm, find the position, nature and height of the image.

Q 13 | Page 198

At what distance from a concave mirror focal length 10 cm should an object 2 cm long be placed in order to get an erect image 6 cm tall?

Q 14 | Page 198

When an object is placed at a distance of 15 cm from a concave mirror, its image is formed at 10 cm in front of the mirror. Calculate the focal length of the mirror.

Q 15 | Page 198

An object 3 cm high is placed at a distance of 8 cm from a concave mirror which produces a virtual image 4.5 cm high:

(i) What is the focal length of the mirror?
(ii) What is the position of image?
(iii) Draw a ray-diagram to show the formation of image.

Q 16 | Page 198

A converging mirror forms a real image of height 4 cm of an object of height 1 cm placed 20 cm away from the mirror:

(i) Calculate the image distance.
(ii) What is the focal length of the mirror?

Q 17 | Page 198

An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed so that a sharp focussed image can be obtained? Find the size and nature of image.

Q 18 | Page 199

An object 3 cm high is placed at a distance of 10 cm in front of a converging mirror of focal length 20 cm. Find the position, nature and size of the image formed.

Q 19 | Page 199

A concave mirror has a focal length of 4 cm and an object 2 cm tall is placed 9 cm away from it. Find the nature, position and size of the image formed.

Q 20 | Page 199

When an object is placed 20 cm from a concave mirror, a real image magnified three times is formed. Find:

(a) the focal length of the mirror.
(b) Where must the object be placed to give a virtual images three times the height of the object?

Q 21 | Page 199

A dentist's mirror has a radius of curvature of 3 cm. How far must it be placed from a small dental cavity to give a virtual image of the cavity that is magnified five times?

Q 22 | Page 199

A large concave mirror has a radius of curvature of 1.5 m. A person stands 10 m in front of the mirror. Where is the person's image?

Q 23 | Page 199

An object of 5.0 cm size is placed at a distance of 20.0 cm from a converging mirror of focal length 15.0 cm. At what distance from the mirror should a screen be placed to get the sharp image? Also calculate the size of the image.

Q 24 | Page 199

A concave mirror produces three times enlarged virtual image of an object placed at 10 cm in front of it. Calculate the radius of curvature of the mirror.

Q 25 | Page 199

A bright object 50 mm high stands on the axis of a concave mirror of focal length 100 mm and at a distance of 300 mm from the concave mirror. How big will the image be?

Q 26 | Page 199

How far should an object be placed from the pole of a converging mirror of focal length 20cm to form a real image of the size exactly 1/4th the size of the object?

Q 27 | Page 199

When an object is placed at a distance of 50 cm from a concave spherical mirror, the magnification produced is, -1/2. Where should the object be placed to get a magnification of, -1/5?

Q 27 | Page 200

When a light ray passes from air into glass, what happens to its speed? Draw a diagram to show which way the ray of light bends.

Q 28 | Page 199

An object is placed (a) 20 cm, (b) 4 cm, in front of a concave mirror of focal length 12 cm. Find the nature and position of the image formed in each case.

Q 28.2 | Page 200

A coin in a glass tumbler appears to rise as the glass tumbler is slowly filled with water. Name the phenomenon responsible for this effect.

Q 29 | Page 199

A concave mirror produces a real image 1 cm tall of an object 2.5 mm tall placed 5 cm from the mirror. Find the position of the image and the focal length of the mirror.

Q 30 | Page 199

A man holds a spherical shaving mirror of radius of curvature 60 cm, and focal length 30 cm, at a distance of 15 cm, from his nose. Find the position of image, and calculate the magnification.

Q 30 | Page 199

A man holds a spherical shaving mirror of radius of curvature 60 cm, and focal length 30 cm, at a distance of 15 cm, from his nose. Find the position of image, and calculate the magnification.

Q 31 | Page 199

An object is 24 cm away from a concave mirror and its image is 16 cm from the mirror. Find the focal length and radius of curvature of the mirror, and the magnification of the image.

Q 31 | Page 199

An object is 24 cm away from a concave mirror and its image is 16 cm from the mirror. Find the focal length and radius of curvature of the mirror, and the magnification of the image.

Q 31 | Page 199

An object is 24 cm away from a concave mirror and its image is 16 cm from the mirror. Find the focal length and radius of curvature of the mirror, and the magnification of the image.

Q 31.1 | Page 199

An object is placed just outside the principal focus of concave mirror. Draw a ray diagram to show how the image is formed, and describe its size, position and nature.

Q 31.2 | Page 199

If the object is moved further away from the mirror, what changes are there in the position and size of the image?

Q 32 | Page 199

An object is 24 cm away from a concave mirror and its image is 16 cm from the mirror. Find the focal length and radius of curvature of the mirror, and the magnification of the image.

Q 33 | Page 199

Magnification produced by a convex mirror is always:

(a) more than 1
(b) less than 1
(c) equal to 1
(d) more or less than 1

Q 33 | Page 199

Linear magnification produced by a concave mirror may be:

(a) less than 1 or equal to 1
(b) more than 1 or equal than 1
(c) less than 1, more than 1 or equal to 1
(d) less than 1 or more than 1

Q 34 | Page 199

Magnification produced by a convex mirror is always:

(a) more than 1
(b) less than 1
(c) equal to 1
(d) more or less than 1

Q 35 | Page 199

In order to obtain a magnification of −2 (minus 2) with a concave mirror, the object should be placed:

(a) between pole and focus
(b) between focus and centre of curvature
(c) at the centre of curvature
(d) beyond the centre of curvature

Q 35 | Page 199

In order to obtain a magnification of −2 (minus 2) with a concave mirror, the object should be placed:

(a) between pole and focus
(b) between focus and centre of curvature
(c) at the centre of curvature
(d) beyond the centre of curvature

Q 36 | Page 199

A concave mirror produces magnification of +4. The object is placed:

(a) at the focus
(b) between focus and centre of curvature
(c) between focus and pole
(d) between the centre of curvature

Q 37 | Page 199

If a magnification of, −1 (minus one) is to be obtained by using a converging mirror, then the object has to be placed:

(a) between pole and focus
(b) at the centre of curvature
(c) beyond the centre of curvature
(d) at infinity

Q 37 | Page 200

If a magnification of, −1 (minus one) is to be obtained by using a converging mirror, then the object has to be placed:

(a) between pole and focus
(b) at the centre of curvature
(c) beyond the centre of curvature
(d) at infinity

Q 38 | Page 199

In order to obtain a magnification of, −0.6 (minus 0.6) with a concave mirror, the object must be placed:

(a) at the focus
(b) between pole and focus
(c) between focus and centre of curvature
(d) beyond the centre of curvature

Q 38 | Page 200

In order to obtain a magnification of, −0.6 (minus 0.6) with a concave mirror, the object must be placed:

(a) at the focus
(b) between pole and focus
(c) between focus and centre of curvature
(d) beyond the centre of curvature

Q 39 | Page 200

An object is placed at a large distance in front of a concave mirror of radius of curvature 40 cm. The image will be formed in front of the mirror at a distance:

(a) 20 cm
(b) 30 cm
(c) 40 cm
(d) 50 cm

Q 40 | Page 200

In order to obtain a magnification of, −1.5 with a concave mirror of focal length 16 cm, the object will have to be placed at a distance

(a) between 6 cm and 16 cm
(b) between 32 cm and 16 cm
(c) between 48 cm and 32 cm
(d) beyond 64 cm

Q 40 | Page 199

In order to obtain a magnification of, −1.5 with a concave mirror of focal length 16 cm, the object will have to be placed at a distance

(a) between 6 cm and 16 cm
(b) between 32 cm and 16 cm
(c) between 48 cm and 32 cm
(d) beyond 64 cm

Q 41 | Page 200

Linear magnification (m) produced by a rear view mirror fitted in vehicles:

(a) is equal to one
(b) is less than one
(c) is more than one
(d) can be more less than one depending on the position of object

Q 41 | Page 200

Linear magnification (m) produced by a rear view mirror fitted in vehicles:

(a) is equal to one
(b) is less than one
(c) is more than one
(d) can be more less than one depending on the position of object

Q 42 | Page 200

Between which two points of concave mirror should an object be placed to obtain a magnification of:

(a) −3
(b) +25
(c) −0.4

Q 42 | Page 200

Between which two points of concave mirror should an object be placed to obtain a magnification of:

(a) −3
(b) +25
(c) −0.4

Q 43 | Page 200

At what distance from a concave mirror of focal length 10 cm should an object be placed so that:

its virtual image is formed 20 cm from the mirror?

Q 43.1 | Page 200

At what distance from a concave mirror of focal length 10 cm should an object be placed so that:

its real image is formed 20 cm from the mirror?

Q 43.2 | Page 200

At what distance from a concave mirror of focal length 10 cm should an object be placed so that:

its virtual image is formed 20 cm from the mirror?

Q 44 | Page 200

If a concave mirror has a focal length of 10 cm, find the two positions where an object can be placed to give, in each case, an image twice the height of the object.

Q 45 | Page 200

A mirror forms an image which is 30 cm from an object and twice its height.

(a) Where must the mirror be situated?
(b) What is the radius of curvature?
(c) Is the mirror convex or concave?

#### Chapter 4: Reflection of Light solutions [Pages 205 - 207]

Q 1 | Page 205

What type of image/images are formed by:

a concave mirror?

Q 1 | Page 205

What type of image/images are formed by:

a convex mirror?

Q 1.1 | Page 205

What type of image/images are formed by:

a convex mirror?

Q 1.2 | Page 205

What type of image/images are formed by:

a concave mirror?

Q 2 | Page 205

Which mirror has a wider field of view?

Q 3 | Page 205

If you want to see an enlarged image of your face, state whether you will use a concave mirror or a convex mirror?

Q 4 | Page 205

Which mirror always produces a virtual, erect and diminished image of an object?

Q 5 | Page 205

An object is placed at a long distance in front of a convex mirror of radius of curvature 30 cm. State the position of its image.

Q 6 | Page 205

Name the spherical mirror which can produce a real and diminished image of an object.

Q 6 | Page 205

Name the spherical mirror which can produce a real and diminished image of an object.

Q 7 | Page 205

Name the spherical mirror which can produce a virtual and diminished image of an object.

Q 8 | Page 205

One wants to see a magnified image of an object in a mirror. What type of mirror should one use?

Q 9.1 | Page 205

Name the mirror which can give:

an erect and diminished image of an object.

Q 9.2 | Page 205

Name the mirror which can give:

an erect and enlarged image of an object.

Q 10 | Page 205

State whether the following statement is true or false:
A diverging mirror is used as a rear-view mirror.

Q 11 | Page 205

What type of mirror should be used:

as a shaving mirror?

Q 11.1 | Page 205

What type of mirror should be used:

as a shaving mirror?

Q 11.2 | Page 205

What type of mirror should be used:

as a shaving mirror?

Q 12 | Page 205

Which type or mirror is usually used as a rear-view mirror in motor cars?

Q 13 | Page 205

What kind of mirrors are used in big shopping centres to watch the activities of the customers?

Q 13 | Page 205

What kind of mirrors are used in big shopping centres to watch the activities of the customers?

Q 14 | Page 205

A ray of light of going towards the focus of a convex mirror becomes parallel to the principal axis after reflection from the mirror. Draw a labelled diagram to represent this situation.

Q 15 | Page 205

Fill in the following blank with a suitable word:
A ray of light which is parallel to the principal axis of a convex mirror, appears to be coming from ............ after reflection from the mirror.

Q 16 | Page 205

Why do we prefer a convex mirror as a rear-view mirror in vehicles?

Q 17 | Page 205

Why can you not use a concave mirror as a rear-view mirror in vehicles?

Q 18.1 | Page 205

Where would the image be formed by a convex mirror if the object is placed:

between infinity and pole of the mirror?

Draw labelled ray-diagrams to show the formation of image in both the case.

Q 18.2 | Page 205

Where would the image be formed by a convex mirror if the object is placed:

at infinity?

Draw labelled ray-diagrams to show the formation of image in both the case.

Q 19 | Page 206

The shiny outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror:

Which type of spherical mirror will it provide?

Q 19 | Page 206

The shiny outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror:

State whether this spherical mirror will diverge or converge light rays.

Q 19.1 | Page 206

The shiny outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror:

What will be the focal length of this mirror?

Q 19.2 | Page 206

The shiny outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror:

Which type of spherical mirror will it provide?

Q 19.3 | Page 206

The shiny outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror:

State whether this spherical mirror will diverge or converge light rays.

Q 20 | Page 206

What is the advantage of using a convex mirror as  rear-view mirror in vehicles as compared to a plane mirror? Illustrate your answer with the help of labelled diagrams.

Q 20 | Page 206

What is the advantage of using a convex mirror as  rear-view mirror in vehicles as compared to a plane mirror? Illustrate your answer with the help of labelled diagrams.

Q 21 | Page 206

Give two uses of a convex mirror. Explain why you would choose convex mirror for these uses.

Q 22 | Page 206

What would your image look like if you stood close to a large:

convex mirror?

Q 22.1 | Page 206

What would your image look like if you stood close to a large:

convex mirror?

Q 22.2 | Page 206

What would your image look like if you stood close to a large:

concave mirror?

Q 23 | Page 206

Which of the following are concave mirrors and which convex mirrors?

Shaving mirrors, Car headlight mirror, Searchlight mirror, Driving mirror, Dentist's inspection mirror, Touch mirror, Staircase mirror in a double-decker bus, Make-up mirror, Solar furnace mirror, Satellite TV dish, Shop security mirror.

Q 23.1 | Page 206

Which of the following are concave mirrors and which convex mirrors?

Q 23.2 | Page 206

Which of the following are concave mirrors and which convex mirrors?

Shaving mirrors, Car headlight mirror, Searchlight mirror, Driving mirror, Dentist's inspection mirror, Touch mirror, Staircase mirror in a double-decker bus, Make-up mirror, Solar furnace mirror, Satellite TV dish, Shop security mirror.

Q 24 | Page 206

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

Q 25 | Page 206

If a driver has one convex and one plane rear-view mirror, how would the images in each mirror appear different?

Q 25 | Page 206

If a driver has one convex and one plane rear-view mirror, how would the images in each mirror appear different?

Q 26.1 | Page 206

Draw a labelled ray diagram to show the formation of image of an object by a convex mirror. Mark clearly the pole, focus and centre of curvature on the diagram.

Q 26.2 | Page 206

What happens to the image when the object is moved away from the mirror gradually?

Q 26.3 | Page 206

State three characteristics of the image formed by a convex mirror.

Q 27 | Page 206

Draw a labelled ray diagram to show the formation of image in a convex-mirror when the object is at infinity. Mark clearly the pole and focus of the mirror in the diagram.

Q 27.1 | Page 206

Draw a labelled ray diagram to show the formation of image in a convex-mirror when the object is at infinity. Mark clearly the pole and focus of the mirror in the diagram.

Q 27.2 | Page 206

State three characteristics of the image formed by a convex mirror.

Q 27.3 | Page 206

Draw diagram to show how a convex mirror can be used to give a large field of view.

Q 28 | Page 206

The image formed by a spherical mirror is virtual. The mirror will be:

(a) concave
(b) convex
(c) either concave or convex
(d) metallic

Q 29 | Page 206

Whatever be the position of the object, the image formed by a mirror is virtual, erect and smaller than the object. The mirror then must be:

(a) plane
(b) concave
(c) convex
(d) either concave or convex

Q 29 | Page 206

Whatever be the position of the object, the image formed by a mirror is virtual, erect and smaller than the object. The mirror then must be:

(a) plane
(b) concave
(c) convex
(d) either concave or convex

Q 30 | Page 206

The mirror used by a dentist to examine the teeth of a person is:
(d) any one of the above

(a) convex
(b) concave
(c) plane
(d) any one of the above

Q 30 | Page 206

The mirror used by a dentist to examine the teeth of a person is:
(d) any one of the above

(a) convex
(b) concave
(c) plane
(d) any one of the above

Q 31 | Page 206

If the image formed is always virtual, the mirror can be:

(a) concave or convex
(b) concave or plane
(c) convex or plane
(d) only convex

Q 31 | Page 206

If the image formed is always virtual, the mirror can be:

(a) concave or convex
(b) concave or plane
(c) convex or plane
(d) only convex

Q 32 | Page 206

A concave mirror cannot be used as:

(a) a magnifying mirror
(b) a torch reflector
(c) a dentist's mirror
(d) a real view mirror

Q 33 | Page 206

A boy is standing in front of and close to a special mirror. He finds the image of his head bigger than normal, the middle part of his body of the same size, and his legs smaller than normal. The special mirror is made up of three types of mirrors in the following order from top downwards:

(a) Convex, Plane, Concave
(b) Plane, Convex, Concave
(c) Concave, Plane, Convex
(d) Convex, Concave, Plane

Q 34 | Page 207

The mirror which can form a magnified image of an object is:

(a) convex mirror
(b) plane mirror
(c) concave mirror
(d) both convex and concave mirror

Q 35 | Page 207

A real image of an object is to be obtained. The mirror required for this purpose is:

(a) convex
(b) concave
(c) plane
(d) either convex or concave

Q 36 | Page 207

Consider two statements A and B given below:
A : real image is always inverted
B :  virtual image is always erect
Out of these two statements:

(a) only A is true
(b) only B is true
(c) both A and B are true
(d) none is true

Q 37 | Page 207

The diagrams show the appearance of a fork when placed in front of and close to two mirrors A and B, turn by turn.
Figure

(a) Which mirror is convex
(b) Which mirror is concave

Q 37 | Page 207

The diagrams show the appearance of a fork when placed in front of and close to two mirrors A and B, turn by turn.
Figure

(a) Which mirror is convex
(b) Which mirror is concave

Q 38 | Page 207

The diagram shows a dish antenna which is used to receive television signals from a satellite. The antenna (signal detector) is fixed in front of the curved dish.
Figure

(a) What is the purpose of the dish?
(b) Should it be concave or convex?
(c) Where should the antenna be positioned to receive the strongest possible signals?
(d) Explain what change you would expect in the signals if a larger dish was used.

Q 39 | Page 207

A man standing in front of a special mirror finds his image having a very small head, a fat body and legs of normal size. What is the shape of:

(a) top part of the mirror?
(b) middle part of the mirror?
(c) bottom part of the mirror?

Q 39 | Page 207

A man standing in front of a special mirror finds his image having a very small head, a fat body and legs of normal size. What is the shape of:

(a) top part of the mirror?
(b) middle part of the mirror?
(c) bottom part of the mirror?

Q 40 | Page 207

Two big mirrors A and B are fitted side by side on a wall. A man is standing at such a distance from the wall that he can see the erect image of his face in both the mirrors. When the man starts walking towards the mirrors, he find that the size of his face in mirror A goes on increasing but that in mirror B remains the same.

(a) mirror A is concave and mirror B is convex
(b) mirror A is plane and mirror B is concave
(c) mirror A is concave and mirror B is plane
(d) mirror A is convex and mirror B is concave

#### Chapter 4: Reflection of Light solutions [Pages 209 - 210]

Q 1 | Page 209

An object is kept at a distance of 5 cm in front of a convex mirror of focal length 10 cm. Calculate the position and magnification of the image and state its nature.

Q 2 | Page 209

An object is placed at a distance of 10 cm from a convex mirror of focal length 5 cm.

(a) Draw a ray-diagram showing the formation image
(b) State two characteristics of the image formed
(c) Calculate the distance of the image from mirror.

Q 3 | Page 209

An object is placed at a distance of 6 cm from a convex mirror of focal length 12 cm. Find the position and nature of the image.

Q 4 | Page 209

An object placed 20 cm in front of a mirror is found to have an image 15 cm (a) in front of it, (b) behind the mirror. Find the focal length of the mirror and the kind of mirror in each case.

Q 5 | Page 209

An arrow 2.5 cm high is placed at a distance of 25 cm from a diverging mirror of focal length 20 cm. Find the nature, position and size of the image formed.

Q 6 | Page 209

A convex mirror used as a rear-view mirror in a car has a radius of curvature of 3 m. If a bus is located at a distance of 5 m from this mirror, find the position of image. What is the nature of the image?

Q 6 | Page 209

A convex mirror used as a rear-view mirror in a car has a radius of curvature of 3 m. If a bus is located at a distance of 5 m from this mirror, find the position of image. What is the nature of the image?

Q 7 | Page 209

A diverging mirror of radius of curvature 40 cm forms an image which is half the height of the object. Find the object and image positions.

Q 7 | Page 209

A diverging mirror of radius of curvature 40 cm forms an image which is half the height of the object. Find the object and image positions.

Q 8 | Page 209

The radius of curvature of a convex mirror used as a rear view mirror in a moving car is 12.0 m. A truck is coming from behind it at a distance of 3.54 m. Calculate (a) position, and (b) size of the image relative to the size of the truck. What will be the nature of the image?

Q 8 | Page 209

The radius of curvature of a convex mirror used as a rear view mirror in a moving car is 12.0 m. A truck is coming from behind it at a distance of 3.54 m. Calculate (a) position, and (b) size of the image relative to the size of the truck. What will be the nature of the image?

Q 9 | Page 209

An object 1 cm tall is placed 30 cm in front of a convex mirror of focal length 20 cm. Find the size and position of the image formed by the convex mirror.

Q 9 | Page 209

An object 1 cm tall is placed 30 cm in front of a convex mirror of focal length 20 cm. Find the size and position of the image formed by the convex mirror.

Q 9.1 | Page 209

Draw a diagram to represent a convex mirror. On this diagram mark principal axis, principal focus F and the centre of C if the focal length of convex mirror is 3 cm.

Q 9.2 | Page 209

An object 1 cm tall is placed 30 cm in front of a convex mirror of focal length 20 cm. Find the size and position of the image formed by the convex mirror.

Q 10.1 | Page 209

A shop security mirror 5.0 m from certain items displayed in the shop produces on-tenth magnification.

What is the type of mirror?

Q 10.2 | Page 209

A shop security mirror 5.0 m from certain items displayed in the shop produces on-tenth magnification.

What is the radius of curvature of the mirror?

Q 11 | Page 210

An object is placed 15 cm from (a) a converging mirror, and (b) a diverging mirror, of radius of curvature 20 cm. Calculate the image position and magnification in each case.

Q 11 | Page 210

An object is placed 15 cm from (a) a converging mirror, and (b) a diverging mirror, of radius of curvature 20 cm. Calculate the image position and magnification in each case.

Q 12 | Page 210

An object 20 cm from a spherical mirror gives rise to virtual image 15 cm behind the mirror. Determine the magnification of the image and the type of mirror used.

## Lakhmir Singh solutions for Class 10 Science chapter 4 - Reflection of Light

Lakhmir Singh solutions for Class 10 Science chapter 4 (Reflection of Light) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CBSE Physics for Class 10 (2019 Exam) solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 10 Science chapter 4 Reflection of Light are Some Natural Phenomena Due to Sunlight, Atmospheric Refraction, Dispersion by a Prism, Applications of Spherical Mirrors and Lenses, Defects of Vision and Their Correction, Concept of Human Eye, Power of a Lens, Spherical Mirrors, Image Formation by Spherical Mirrors - Concave Mirror, Representation of Images Formed by Spherical Mirrors Using Ray Diagrams - Concave Mirror, Mirror Formula and Magnification, Velocity of Light, Sign Convention for Reflection by Spherical Mirrors, Lens Formula and Magnification, Refraction Through a Rectangular Glass Slab, Refractive Index, Refraction by Spherical Lenses, Image Formation by Lenses - Convex Lens, Image Formation in Lenses Using Ray Diagrams - Convex Lens, Sign Convention for Spherical Lenses, Introduction, Image Formation by Spherical Mirrors - Convex Mirror, Representation of Images Formed by Spherical Mirrors Using Ray Diagrams - Convex Mirror, Image Formation by Lenses - Concave Lens, Image Formation in Lenses Using Ray Diagrams - Concave Lens, Light Reflection and Refraction Introduction.

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