NCERT Textbook: Light: Mirrors and Lenses | Science Class 8 PDF Download

 Page 1


152
Curiosity — Textbook of Science for Grade 8
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 
  ?
Chapter 10.indd   152 Chapter 10.indd   152 6/28/2025   6:00:41 PM 6/28/2025   6:00:41 PM
Page 2


152
Curiosity — Textbook of Science for Grade 8
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 
  ?
Chapter 10.indd   152 Chapter 10.indd   152 6/28/2025   6:00:41 PM 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?
 z Now flip the spoon and repeat the same steps.
Did you notice that the shiny metallic spoon acted 
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. 
(a) (b)
Fig. 10.1: Image formed in a shiny 
metallic spoon from its (a) Inner curved 
surface; (b) Outer curved surface
Chapter 10.indd   153 Chapter 10.indd   153 6/28/2025   6:00:46 PM 6/28/2025   6:00:46 PM
Page 3


152
Curiosity — Textbook of Science for Grade 8
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 
  ?
Chapter 10.indd   152 Chapter 10.indd   152 6/28/2025   6:00:41 PM 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?
 z Now flip the spoon and repeat the same steps.
Did you notice that the shiny metallic spoon acted 
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. 
(a) (b)
Fig. 10.1: Image formed in a shiny 
metallic spoon from its (a) Inner curved 
surface; (b) Outer curved surface
Chapter 10.indd   153 Chapter 10.indd   153 6/28/2025   6:00:46 PM 6/28/2025   6:00:46 PM
154
Curiosity — Textbook of Science for Grade 8
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)
Fig. 10.2: (a) Concave mirror; 
(b) Its representation
(a) (b)
Fig. 10.3: (a) Convex mirror; 
(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.
Imaginary 
hollow 
sphere
A piece of 
imaginary 
hollow sphere
Concave 
mirror
Convex 
mirror
Coated 
surface
Reflecting 
surface
Reflecting 
surface
Chapter 10.indd   154 Chapter 10.indd   154 6/28/2025   6:00:55 PM 6/28/2025   6:00:55 PM
Page 4


152
Curiosity — Textbook of Science for Grade 8
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 
  ?
Chapter 10.indd   152 Chapter 10.indd   152 6/28/2025   6:00:41 PM 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?
 z Now flip the spoon and repeat the same steps.
Did you notice that the shiny metallic spoon acted 
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. 
(a) (b)
Fig. 10.1: Image formed in a shiny 
metallic spoon from its (a) Inner curved 
surface; (b) Outer curved surface
Chapter 10.indd   153 Chapter 10.indd   153 6/28/2025   6:00:46 PM 6/28/2025   6:00:46 PM
154
Curiosity — Textbook of Science for Grade 8
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)
Fig. 10.2: (a) Concave mirror; 
(b) Its representation
(a) (b)
Fig. 10.3: (a) Convex mirror; 
(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.
Imaginary 
hollow 
sphere
A piece of 
imaginary 
hollow sphere
Concave 
mirror
Convex 
mirror
Coated 
surface
Reflecting 
surface
Reflecting 
surface
Chapter 10.indd   154 Chapter 10.indd   154 6/28/2025   6:00:55 PM 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 
with their reflecting surfaces facing upwards. 
 z Now view them from the side, keeping your 
eye at their level, to identify whether the 
reflecting surface is curved inwards or 
outwards (Fig. 10.4).
Fig. 10.4: Identifying concave and convex mirrors from their side view 
Concave mirror
Convex mirror
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 
mirror, two small wooden blocks 
or something similar to place the 
mirrors in an upright position, and 
a small toy or some other object.
 z Place the two mirrors side by side 
in an upright position on a table. 
Keep the object in front of them at 
a small distance (3–4 cm away) as 
shown in Fig. 10.5a. What kind of 
images do you see in each mirror? 
Are the images of the same size as 
the object? Are they erect? Do you 
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.
How can we distinguish 
between concave and 
convex mirrors?
Fig. 10.5: An object placed in front of concave and 
convex mirrors at (a) Small distance; (b) Large distance
(a) (b)
Concave 
mirror
Convex 
mirror
Convex 
mirror
Concave 
mirror
Chapter 10.indd   155 Chapter 10.indd   155 6/28/2025   6:01:07 PM 6/28/2025   6:01:07 PM
Page 5


152
Curiosity — Textbook of Science for Grade 8
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 
  ?
Chapter 10.indd   152 Chapter 10.indd   152 6/28/2025   6:00:41 PM 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?
 z Now flip the spoon and repeat the same steps.
Did you notice that the shiny metallic spoon acted 
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. 
(a) (b)
Fig. 10.1: Image formed in a shiny 
metallic spoon from its (a) Inner curved 
surface; (b) Outer curved surface
Chapter 10.indd   153 Chapter 10.indd   153 6/28/2025   6:00:46 PM 6/28/2025   6:00:46 PM
154
Curiosity — Textbook of Science for Grade 8
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)
Fig. 10.2: (a) Concave mirror; 
(b) Its representation
(a) (b)
Fig. 10.3: (a) Convex mirror; 
(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.
Imaginary 
hollow 
sphere
A piece of 
imaginary 
hollow sphere
Concave 
mirror
Convex 
mirror
Coated 
surface
Reflecting 
surface
Reflecting 
surface
Chapter 10.indd   154 Chapter 10.indd   154 6/28/2025   6:00:55 PM 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 
with their reflecting surfaces facing upwards. 
 z Now view them from the side, keeping your 
eye at their level, to identify whether the 
reflecting surface is curved inwards or 
outwards (Fig. 10.4).
Fig. 10.4: Identifying concave and convex mirrors from their side view 
Concave mirror
Convex mirror
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 
mirror, two small wooden blocks 
or something similar to place the 
mirrors in an upright position, and 
a small toy or some other object.
 z Place the two mirrors side by side 
in an upright position on a table. 
Keep the object in front of them at 
a small distance (3–4 cm away) as 
shown in Fig. 10.5a. What kind of 
images do you see in each mirror? 
Are the images of the same size as 
the object? Are they erect? Do you 
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.
How can we distinguish 
between concave and 
convex mirrors?
Fig. 10.5: An object placed in front of concave and 
convex mirrors at (a) Small distance; (b) Large distance
(a) (b)
Concave 
mirror
Convex 
mirror
Convex 
mirror
Concave 
mirror
Chapter 10.indd   155 Chapter 10.indd   155 6/28/2025   6:01:07 PM 6/28/2025   6:01:07 PM
156
Curiosity — Textbook of Science for Grade 8
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 
mirror which provides an enlarged view of teeth 
when held close to the teeth inside the mouth 
(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 
Fig. 10.6: Use of concave mirror (a) As a 
reflector of a torch; (b) By a dentist
(b) (a)
Chapter 10.indd   156 Chapter 10.indd   156 6/28/2025   6:01:13 PM 6/28/2025   6:01:13 PM