Light: Mirrors and

Lenses
10
Probe and ponder

z Can we make mirrors which can give enlarged or diminished

images?
z On side-view mirrors of vehicles, there is a warning that says
“Objects in mirror are closer than they appear”. Why is this
warning written there?
z Why is there a curved line on some reading glasses?
z Share your questions

152
Curiosity — Textbook of Science for Grade 8

Chapter 10.indd 152 6/28/2025 6:00:41 PM

 Chapter 10 — Light: Mirrors and Lenses 153

During the summer holidays, Meena went to a science centre with

her family. The centre had many fascinating displays on nature,
space, and technology. While her parents explored a section on
saving water and electricity, Meena and her brother wandered off
to look around. In one corner, Meena noticed a row of unusual,
curved mirrors. Curious, she stepped closer and looked into one.
Her face appeared unusually large, while her brother, standing
a little farther away, looked upside down! At another mirror, she
saw a tiny version of herself. Meena was puzzled.
She remembered doing activities with a mirror earlier where
the image formed by the mirror was of the same size as the object
and was erect (in the chapter ‘Light: Shadows and Reflections’
in Curiosity, Grade 7). Seeing her confusion, a guide from the
science centre walked up to her and smiled. “These are not plane
mirrors,” the guide explained. “These are spherical mirrors.
When the mirror is curved inward or outward, your image looks
different in them!” Meena’s curiosity grew and she decided to
talk to her teacher about these spherical mirrors.

10.1 What Are Spherical Mirrors?

Activity 10.1: Let us explore

z Take a shiny metallic spoon and hold its

curved surface close to your face. Can you
see your image in it?
z Notice the image of your face. Is it different
from the image you see in a plane mirror?
z While observing the image, slowly move the
spoon away from your face. Do you observe
any change in the image?
(a) (b)
z Now flip the spoon and repeat the same steps. Fig. 10.1: Image formed in a shiny
Did you notice that the shiny metallic spoon acted metallic spoon from its (a) Inner curved
surface; (b) Outer curved surface
like a mirror and you could see your image in it?
When you looked at the inner side of the spoon which is curved
inwards, you must have observed that the image was inverted
(Fig. 10.1a). When you looked at the outer side of the spoon which
bulges outwards, the image of your face was erect but smaller in
size (Fig. 10.1b).
Curved mirrors, like the spoon, can also be specially made.
Spherical mirrors are a common type of curved mirrors which
are shaped like a part of a hollow glass sphere. Mirrors, whose
reflecting surfaces are spherical are called spherical mirrors.

Chapter 10.indd 153 6/28/2025 6:00:46 PM

 The reflecting surface of the spherical mirror may be curved
inwards or outwards. A spherical mirror, which has a reflecting
surface that curves inwards, is called a concave mirror
(Fig. 10.2a). Its schematic representation is shown in Fig. 10.2b.
The outline of the surface of the mirror is circular.

(a) (b) (a) (b)

Fig. 10.2: (a) Concave mirror; Fig. 10.3: (a) Convex mirror;
(b) Its representation (b) Its representation

A spherical mirror which has a reflecting surface that curves

outwards is called a convex mirror (Fig. 10.3a). Its schematic
representation is shown in Fig. 10.3b.
In the representation of both the mirrors, the non-reflecting
surface of the mirror is shown as shaded.

A step further

The shape of a spherical mirror is such that it can be thought of as

a part of an imaginary hollow sphere. However, remember that
spherical mirrors are not made by slicing a hollow glass sphere.
Instead, they are created by grinding and polishing a flat glass
piece into a curved surface. If a reflective coating (like a thin layer
of aluminium) is applied on the outer curved surface, it forms
a concave mirror. If the coating is applied on the inner curved
surface, it forms a convex mirror.
Coated
Imaginary surface
hollow
sphere

Reflecting Reflecting
surface surface

A piece of
imaginary Concave Convex
hollow sphere mirror mirror

154
Curiosity — Textbook of Science for Grade 8

Chapter 10.indd 154 6/28/2025 6:00:55 PM

 Chapter 10 — Light: Mirrors and Lenses 155

Activity 10.2: Let us distinguish

z Place concave and convex mirrors on a table How can we distinguish
with their reflecting surfaces facing upwards. between concave and
z Now view them from the side, keeping your convex mirrors?
eye at their level, to identify whether the
reflecting surface is curved inwards or
outwards (Fig. 10.4).

Convex mirror

Concave mirror
Fig. 10.4: Identifying concave and convex mirrors from their side view

10.2 What Are the Characteristics of Images

Formed by Spherical Mirrors?

Activity 10.3: Let us explore

z Take a concave mirror, a convex Concave Convex
mirror, two small wooden blocks mirror mirror
or something similar to place the
mirrors in an upright position, and
a small toy or some other object. Convex
z Place the two mirrors side by side mirror
in an upright position on a table.
Keep the object in front of them at Concave
a small distance (3–4 cm away) as mirror
shown in Fig. 10.5a. What kind of
images do you see in each mirror? (a) (b)
Are the images of the same size as Fig. 10.5: An object placed in front of concave and
the object? Are they erect? Do you convex mirrors at (a) Small distance; (b) Large distance
see lateral inversion in the images?
Write down your observations in your notebook.
z Now slowly move the object away from the mirrors. What
changes do you see in the images in both the mirrors? Do
the images become smaller or larger? Do they continue to be
erect? Again, note down your observations.
z Repeat the steps with each mirror individually.
z Analyse your observations and draw conclusions.

Chapter 10.indd 155 6/28/2025 6:01:07 PM

 In the concave mirror, when the object is placed close to the
mirror, the image is erect but larger than the object in size, that is,
enlarged. However, when the object is moved farther away, the
image becomes inverted. Initially, the image is enlarged in size and
then keeps getting smaller. In case of a convex mirror, the image
is always erect and smaller than the object, that is diminished.
However, the size of the image decreases slightly as the object is
moved away from the convex mirror.
This activity shows that spherical mirrors (concave and
convex) behave differently from plane mirrors. A plane mirror
always forms an erect image of the same size as the object.
However, in the concave and convex mirrors, the size of the
image changes as the distance of the object from the mirror
changes. In addition, in the case of a concave mirror, the image
also gets inverted when the object is taken away from the mirror.
Lateral inversion of the image is seen in all three types of mirrors.

I just got an idea. We can also identify

whether a mirror is plane, or concave,
or convex by looking at the images of an
object formed in them!

Yes. But where do we

find concave and convex
mirrors being used in
our surroundings?

The reflectors of torches, headlights of cars

and scooters are concave in shape (Fig. 10.6a).
Have you ever noticed a dental mirror used by
a dentist for inspecting teeth? It is a concave
(a) (b) mirror which provides an enlarged view of teeth
Fig. 10.6: Use of concave mirror (a) As a when held close to the teeth inside the mouth
reflector of a torch; (b) By a dentist (Fig. 10.6b).

A step further

Do you remember learning about the use of telescope in the chapter

‘Beyond Earth’ in Curiosity, Grade 6? Most modern telescopes are
reflecting telescope that use curved mirrors, with the main mirror
being a large concave mirror.

Look at the side-view mirrors on vehicles. These mirrors are

convex. They always form an erect image of the traffic behind and
smaller than the actual vehicles. Also, since the convex mirror is

156
Curiosity — Textbook of Science for Grade 8

Chapter 10.indd 156 6/28/2025 6:01:13 PM

 Chapter 10 — Light: Mirrors and Lenses 157

(a) (b) (c)

Fig. 10.7: Use of convex mirror as a (a) Side-view mirror; (b) Road safety mirror; (c)
Surveillance mirror

curved outside, it provides a much wider area of the road behind.

Further, such convex mirrors are installed at road intersections
or sharp bends to provide drivers
from both sides the visibility of the We have observed images formed by
other side and prevent collisions. three types of mirrors — plane, concave,
Convex mirrors are also installed and convex. But are there any laws
in big stores to monitor a large which govern the image formation?
area to deter thefts.

10.3 What Are the Laws of Reflection?

Let us now repeat an activity which we did earlier in grade 7,
but this time we will extend it further. Do you remember doing
the activity for observing the reflection of a beam of light from a
plane mirror?

Activity 10.4: Let us experiment

z Collect a plane mirror with stand, a torch, a
comb, a paper clip to hold the comb upright, a
sheet of white paper, and a strip of black paper.
z As you did earlier, make a thin slit by covering
(a)
all openings of the comb using black paper,
except for one in the middle.
z Spread a sheet of white paper on a table. Place
the plane mirror upright on it.
z Using the thin slit and torch, obtain a thin beam
of light along the paper and adjust it to fall upon
the mirror as shown in Fig. 10.8a.
z Now, move the slit and torch slightly so that the
(b)
beam of light falls at a different angle on the
Fig. 10.8: A beam of light falling on a
mirror (Fig. 10.8b). Does the reflected beam of mirror (a) At one angle;
light also shift? (b) At another angle

Chapter 10.indd 157 6/28/2025 6:01:25 PM

 Plane mirror
z Make the beam of light fall on the mirror at different angles
and observe how the direction of the reflected beam changes.
To understand this better, let us draw this on a paper, step by
(a)
step. But before doing that, let us learn how to represent light.
We often represent light by straight lines with arrows, or rays.
O
Rays indicate the path along which light travels. Do you remember
learning earlier that the light travels along a straight line?
z Draw a line showing the position of the plane mirror.
Also, draw lines with arrows (rays) indicating the beam of
light falling on the mirror and the reflected beam of light as
shown in Fig. 10.9a.
(b)
The ray of light that falls on the mirror is called the incident
ray. The ray of light that comes back from the mirror is called the
Incident i r Ref lected reflected ray.
ray ray
z Now remove the mirror. From the point where the incident
normal ray strikes the mirror, draw a line making an angle of 90° to the
(c) line representing the mirror. This line is known as the normal
to the reflecting surface at the point of incidence, O (Fig. 10.9b).
The angle between the normal and the incident ray is called
i r the angle of incidence (i) (Fig. 10.9c). The angle between the
normal and the reflected ray is known as the angle of reflection
(r) (Fig. 10.9c).
z On your drawing, measure the angle of incidence and the
(d) angle of reflection and note it in Table 10.1.
Fig. 10.9: (a) Drawing
incident and ref lected
z Repeat the activity several times by changing the angle of
rays; (b) Drawing the incidence.
normal; (c) Angle of z Finally, let the incident beam fall on the mirror along the
incidence and angle of
normal and observe the direction of the reflected beam.
reflection;
(d) Measuring angles What would be the angle of incidence and angle of reflection
in this case? Both the angles would be zero in this case.
Table 10.1: Measuring angles of incidence and reflection

S.No. Angle of incidence (i ) Angle of reflection (r )

Do you notice that both angles in Table 10.1 are nearly

equal? If done carefully, the experiment shows that the angle of
incidence (i) is equal to the angle of reflection (r). This is a law
of reflection.
158
Curiosity — Textbook of Science for Grade 8

Chapter 10.indd 158 6/28/2025 6:01:27 PM

 Chapter 10 — Light: Mirrors and Lenses 159

Activity 10.5: Let us experiment

z Use the same setup as in Activity 10.4,

but place a stiff sheet of chart paper flat
on a table such that part of it extends
beyond the edge of the table.
z Shine a beam of light on the mirror
placed on the sheet and observe the
reflected beam on the extended portion
(Fig. 10.10a).
z Now, bend the extended part of the sheet
along the edge of the table. Do you still (a)
see the reflected beam on the extended
portion?
z Flatten the paper again and observe.
The reflected beam disappears when the
sheet is bent but reappears when it is
flattened again. This shows that the reflected
beam lies in the same plane as that of the
incident beam. Bending the sheet creates a
new plane, breaking this alignment.
The incident ray, the normal to the (b)
mirror at the point of incidence, and the Fig. 10.10: (a) Reflected beam visible along the
reflected ray, all lie in the same plane. extended portion of paper; (b) Reflected beam not
This is another law of reflection. visible along the bent portion of paper

A step further

In the two cases, even though the directions of incident rays are
different, they fall at the same point on the mirror, and thus, the
directions of normal are the same. However, the direction of the
reflected ray is such that the incident ray, the normal at the point of
incidence, and the reflected ray all lie in the same plane in both cases.

Incident ray

Incident ray Normal

Normal
Reflected ray
Reflected ray

Mirror Mirror

Chapter 10.indd 159 6/28/2025 6:01:37 PM

 Are laws of reflection The laws of reflection are valid for all kinds of
applicable to spherical mirrors — plane and spherical. But if multiple
mirrors also? parallel rays fall on the spherical mirrors, we
observe something interesting.

Activity 10.6: Let us explore

z Collect a plane mirror, a concave mirror, a convex

mirror, stand for mirrors, a torch, a comb, and a
(a) paper clip to hold the comb upright.
Plane mirror z Use the same setup as Activity 10.4 again, but instead
of a single slit, leave many openings of the comb
uncovered to obtain multiple parallel beams of light
(Fig. 10.11a).
z Let the multiple parallel beams of light fall upon the
(b)
plane mirror, concave mirror, and convex mirror,
one by one. Observe the reflected beams. Is your
Concave mirror observation similar to what is shown in Fig. 10.11
(b), (c), and (d)?
When multiple parallel beams of light fall upon a plane
mirror, the multiple reflected beams are also parallel
(Fig. 10.11b). However, when multiple beams of light fall
upon a concave mirror, the multiple reflected beams get
(c) closer, that is, they converge (Fig. 10.11c). Whereas, in
Convex mirror the case of a convex mirror, the multiple reflected beams
spread, that is, they diverge (Fig. 10.11d).
In the case of spherical mirrors, even though each
ray of light follows the laws of reflection, the curved
surface of spherical mirrors causes the parallel beam of
rays to either converge (concave) or diverge (convex) on
(d) reflection depending on the shape of the mirror.
Fig. 10.11: (a) Multiple slits; A step further
Multiple parallel beams of light
fall upon — (b) Plane mirror;
(c) Concave mirror; If we draw what we observed in Activity 10.6, we get the
(d) Convex mirror figures like those shown below.

Plane mirror Concave mirror Convex mirror

160
Curiosity — Textbook of Science for Grade 8

Chapter 10.indd 160 6/28/2025 6:01:51 PM

 Chapter 10 — Light: Mirrors and Lenses 161

So, the concave mirror

converges a light beam
while the convex mirror Since the concave
diverges it. This is indeed mirror converges the
interesting! light beam, wouldn’t
light get concentrated
in a small area?

Activity 10.7: Let us explore

Safety first tsriF ytefaS

Always perform this activity under the supervision of a teacher or
an adult. Do not look towards the Sun or into the mirror reflecting
the Sun. Focus the reflected light only on a piece of paper, not
towards anyone’s face or eyes.

z Take a concave mirror and a sheet of thin paper

or newspaper.
z Hold the concave mirror with its reflecting surface
facing the Sun. Direct the light of the Sun reflected
by the mirror on the sheet of paper.
z Adjust the distance of the paper until you get a
sharp bright spot on it as shown in Fig. 10.12. Concave
z Hold the mirror and the sheet of paper steady mirror
for a few minutes. Does the paper start to burn Fig. 10.12: Converging sunlight on
producing smoke? paper using a concave mirror

The bright spot is formed on the paper because light from the
Sun, after reflection from the mirror, gets concentrated on this
point. This produces sufficient heat at this point which can ignite
the paper.

A step further

Devices which concentrate sunlight into a small area, using mirrors

and lenses, are called solar concentrators. The concentrated sunlight
is used to heat a liquid to produce steam which can be used to
generate electricity or for providing heat for various purposes, such
as large scale cooking or for solar furnaces. Solar furnaces are even
used for melting steel! Do you remember learning in an earlier
chapter, about electric furnaces for melting steel?

Chapter 10.indd 161 6/28/2025 6:02:01 PM

 10.4 What Is a Lens?
Imagine looking through a flat
We explored the images of an
transparent glass window pane — all
object formed by curved mirrors.
But how do objects look when objects look the same size and shape.
viewed through transparent But would those objects continue to
materials with curved surfaces? look the same if the surface of the
transparent material is curved?

Activity 10.8: Let us explore

z Collect a flat strip of glass or clear plastic, such as a flat scale,

few drops of oil, dropper, water, and a paper or book with
some text printed on it.
z Spread a few drops of oil on the surface of glass or plastic
strip and rub it to leave a very thin coating. You can also use
wax instead of oil.
z Using a dropper or your finger, place a small drop of water
on the oiled/waxed spot. (The oil/wax helps the water form a
nice round drop.)
Fig. 10.13: View of text z Examine the water drop. What is the shape of its surface? Is
beneath the water drop it flat or curved inward or curved outward?
z Place the paper underneath the glass/plastic strip such that
the text is directly under the water drop (see Fig. 10.13).
z Now, look down through the water drop at the text below. Do
you find some change in the size of the letters just below the
water drop? Do they look enlarged or smaller?
The surface of the water drop is curved outside. The letters
under the water drop look different — they might appear larger
than the letters nearby! The curved surface of the water drop
made the size of the text look different. This curved drop of water
is acting like a simple lens. Have you seen a magnifying glass as
shown in Fig. 10.14? It is also a lens that helps in reading small
print by making the letters appear bigger.
Fig. 10.14: A magnifying glass A lens is a piece of transparent material,
usually made of glass or plastic, which has
curved surfaces. Like mirrors, lenses can also
be convex or concave.
A lens which is thicker at the middle as
compared to the edges is called a convex lens
(a) (b)
(Fig. 10.15a).
Fig. 10.15: (a) A convex lens;
(b) Its representation
162
Curiosity — Textbook of Science for Grade 8

Chapter 10.indd 162 6/28/2025 6:02:08 PM

 Chapter 10 — Light: Mirrors and Lenses 163

A lens which is thicker at the edges as

compared to the middle is called a concave
lens (Fig. 10.16b).
Unlike mirrors, lenses allow light to pass
through them, and we see things through a
lens rather than in a lens. (a) (b)
Fig. 10.16: (a) A concave lens;
(b) Its representation
What changes can be seen in the
objects when viewed through lenses?

Activity 10.9: Let us experiment

z Collect a convex lens, a concave lens, a lens holder, and a

small object.
z Take the convex lens and place it upright using its holder. (a)
z Place the object behind the convex lens (it may also be placed
on something to bring it up to the level of the lens).
z Look at the object through the lens from the other side of
the lens (Fig. 10.17a) and note your observations in your
notebook.
z Now slowly move the object farther from the lens and keep
observing how the image changes. How does the distance of
the object from the convex lens affect how it looks?
z Now repeat the steps using a concave lens. (b)

z Analyse your observations recorded in your notebook

and compare the images seen through both lenses.
What conclusions do you draw?
When an object is placed behind a convex lens at a small
distance from it and seen through the lens, the object appears
erect and enlarged in size. As the distance between the object
and the convex lens increases, the object appears inverted. It is
initially enlarged in size and then diminishes in size. An object
placed behind a concave lens and seen through the lens, always
appears erect and diminished in size. Its size changes, as its (c)
distance from the lens increases. Fig. 10.17: An object as
seen through a (a) Convex
Do lenses also converge or lens placed at small
distance; (b) Convex lens
diverge the light beam?
placed at large distance;
(c) Concave lens

Chapter 10.indd 163 6/28/2025 6:02:26 PM

 Activity 10.10: Let us investigate
z Collect a thin transparent glass plate, a convex lens, a concave
lens, a torch and a comb to obtain multiple parallel beams of
light, a paper clip to hold the comb upright, two identical
books, and sheets of white paper.
z Using two books placed adjacent to each other, fix the glass
plate or lens upright in between them as shown in Fig. 10.18.
Spread paper sheets on both books.
z Now let the multiple parallel beams of light fall upon the
thin glass plate, convex lens, and concave lens one by one
as shown in Fig. 10.18. Does the parallel beam of light pass
through as it is in all three cases?
z Record and analyse your observations.
The light beam passes through the thin glass plate as it is.
The convex lens converges the light falling on it while the concave
lens diverges the light. A convex lens is also called a converging
lens while a concave lens is called a diverging lens.
Thin transparent glass plate Convex lens Concave lens

(a) (b) (c)

Fig. 10.18: Multiple parallel beams of light fall upon the (a) Thin glass plate;
(b) Convex lens; (c) Concave lens

A step further

If we draw what we observed in Activity 10.10, we get the figures like

those shown below.

Since convex lens converges a light

beam, can it also burn a paper?

164
Curiosity — Textbook of Science for Grade 8

Chapter 10.indd 164 6/28/2025 6:02:47 PM

 Chapter 10 — Light: Mirrors and Lenses 165

Activity 10.11: Let us investigate

z Repeat Activity 10.7 by putting Safety first

a convex lens in the path of
sunrays in place of a concave Do not look at the Sun directly or through
mirror. Could you burn the the lens as it may damage your eyes.
paper?

Where all are the

lenses used?
Convex
lens

Lenses are important and are used

Fig. 10.19: Converging sunlight on
everywhere around us. The eyeglasses that paper using a convex lens
people wear to help them see clearly are
lenses! Cameras, telescopes, and
microscopes all use lenses to work.
Even our eye has a convex lens
inside it. It is quite an amazing lens
that can change its shape, which is
what allows us to read a book or see (a) (b)
something far away. Fig. 10.20: (a) Eyeglasses; (b) Smartphone camera lenses

Snapshots

‹ Image formed by a concave mirror can be enlarged, diminished or of the

same size as the object, and it may be erect or inverted, depending upon
the distance of the object from the mirror.
‹ Image formed by a convex mirror is always erect and diminished in size.
‹ Two laws of reflection are:
{ The angle of incidence is equal to the angle of reflection.
{ The incident ray, the normal to the mirror at the point of incidence,
and the reflected ray, all lie in the same plane.
‹ The laws of reflection are valid for all kinds of mirrors — plane, concave,
and convex.
‹ A concave mirror converges the light beams while a convex mirror
diverges it.
‹ Image formed by a convex lens can be enlarged, diminished or of the
same size as the object, and it may be erect or inverted, depending upon
the distance of the object from the mirror.
‹ Image formed by a concave lens is always erect and diminished in size.
‹ A convex lens converges the light beams while a concave lens diverges it.

Chapter 10.indd 165 6/28/2025 6:02:56 PM

 Keep the curiosity alive

1. A light ray is incident on a mirror and gets reflected by it

(Fig. 10.21). The angle made by the incident ray with the
i r normal to the mirror is 40°. What is the angle made by the
reflected ray with the mirror?
Mirror
(i) 40° (ii) 50° (iii) 45° (iv) 60°
Fig. 10.21
2. Fig. 10.22 shows three different situations where a light ray
falls on a mirror:
(i) The light ray falls along the normal.
(ii) The mirror is tilted, but the
light ray still falls along the
Incident ray
y

normal to the tilted surface.

a
Incident ray

20°
nt r

al
(iii) The mirror is tilted, and the
rm
ide

light ray falls at an angle of

No
Inc

Mir 20° from the normal.

Mirror ror Mir
ror
Draw the reflected ray in each
(a) (b)
(c) case (Use a ruler and protractor
Fig. 10.22 for accurate drawing). What is the
angle of reflection in each case?
3. In Fig. 10.23, the cap of a sketch pen is placed in front of three
types of mirrors.

(i) (ii) (iii)

Fig. 10.23

Match each image with the correct mirror.

Image Mirror
(i) Plane mirror
(ii) Convex mirror
(iii) Concave mirror

166
Curiosity — Textbook of Science for Grade 8

Chapter 10.indd 166 6/28/2025 6:03:05 PM

 Chapter 10 — Light: Mirrors and Lenses 167

4. In Fig. 10.24 the cap of a sketch

pen is placed behind a convex
lens, a concave lens, and a flat
transparent glass piece — all at the
same distance.
Match each image with the correct (i) (ii) (iii)
type of lens or glass. Fig. 10.24

Image Lens/glass type

(i) Flat transparent glass piece
(ii) Convex lens
(iii) Concave lens

5. When the light is incident along the normal on the mirror,

which of the following statements is true:
(i) Angle of incidence is 90°
(ii) Angle of incidence is 0°
(iii) Angle of reflection is 90°
(iv) No reflection of light takes
place in this case
6. Three mirrors — plane, concave
and convex are placed in
Fig. 10.25. On the basis of the
images of the graph sheet formed
in the mirrors, identify the Fig. 10.25
mirrors and write their names
above the mirrors.
7. In a museum, a woman walks towards a large
convex mirror (Fig. 10.26). She will see that:
(i) her erect image keeps decreasing in size.
(ii) her inverted image keeps decreasing in size.
(iii) her inverted image keeps increasing in
size and eventually it becomes erect and
magnified.
(iv) her erect image keeps increasing in size.
8. Hold a magnifying glass over text and identify
the distance where you can see the text bigger Fig. 10.26
than they are written. Now move it away
from the text. What do you notice? Which type of lens is a
magnifying glass?

Chapter 10.indd 167 6/28/2025 6:03:28 PM

 9. Match the entries in Column I with those in Column II.
Column I Column II
(a) Spherical mirror with a reflecting
(i) Concave mirror
surface that curves inwards.
(b) It forms an image which is always erect
(ii) Convex mirror
and diminished in size.
(c) 
Object placed behind it may appear
(iii) Convex lens
inverted at some distance.
(d) Object placed behind it always appears
(iv) Concave lens
diminished in size.

10. The following question is based on Assertion/Reason.

Assertion: Convex mirrors are preferred for observing the
traffic behind us.
Reason: Convex mirrors provide a significantly larger view
area than plane mirrors.
Choose the correct option:
(i) Both Assertion and Reason are correct and Reason is the
correct explanation for Assertion.
(ii) Both Assertion and Reason are correct but Reason is not
the correct explanation for Assertion.
(iii) Assertion is correct but Reason is incorrect.
(iv) Both Assertion and Reason are incorrect.
11. In Fig. 10.27, note that O stands for object, M for mirror, and
I for image.
O M I Which of the following statements is true?
(a) (i) Figure (a) indicates a plane mirror and Figure (b)
indicates a concave mirror.
(ii) Figure (a) indicates a convex mirror and Figure (b)
O M I indicates a concave mirror.
(b) (iii) Figure (a) indicates a concave mirror and Figure (b)
indicates a convex mirror.
Fig. 10.27
(iv) Figure (a) indicates a plane mirror and Figure (b)
indicates a convex mirror.

When?
Prepare some questions based on your
Why not?
Why? Where? learnings so far ...
How long?
.....................................................................................
.....................................................................................
.....................................................................................
168
.....................................................................................
Curiosity — Textbook of Science for Grade 8
.....................................................................................

Chapter 10.indd 168 6/28/2025 6:03:34 PM

 Chapter 10 — Light: Mirrors and Lenses 169

12. Place a pencil behind a transparent glass tumbler

(Fig. 10.28a). Now fill the tumbler halfway with water
(Fig. 10.28b). How does the pencil appear when viewed
through the water? Explain why its shape appears changed.

Discover, design, and debate

z Visit a nearby hospital or the clinic of an ENT specialist, or

(a) (b)
a dentist, with your teacher or parents. Request the doctor
Fig. 10.28
to show you the mirrors used for examining ear, nose,
throat, and teeth. Identify the kind of mirror used in these
instruments.
z Harnessing sunlight is key to
solving future energy challenges.
In devices like solar cookers Science Society
(Fig. 10.29), mirrors are used to
converge sunlight and generate Inter-
heat. In India, such designs are used disciplinary
in villages, thus saving electricity Projects
and reducing fossil fuel use. Think
of a design for a solar cooker for
your school or home and prepare
Fig. 10.29 a detailed proposal for it including
the budget required.
z Use online tools or animation to do virtual experiments with
spherical mirrors and lenses. Move objects in the simulation
and observe how the image changes.

Our scientific heritage

More than 800 years ago, during the time of the great Indian
mathematician Bhāskara II, astronomers used shallow bowls of
water to observe the stars and planets. By carefully looking at their
reflected images through tubes placed at appropriate angles, they
could measure the positions of stars and planets in the sky. Even
though the laws of reflection are not mentioned in literature, their
instruments and methods indicate that they might have understood
it in practice!

I
Reflect on the questions framed by your think ... Shouldn’t it
But we be ...
friends and try to answer ... thought ... Maybe ...
.....................................................................................
.....................................................................................
.....................................................................................
.....................................................................................
.....................................................................................

Chapter 10.indd 169 6/28/2025 6:04:16 PM