Class 7 Science Chapter 3 NCERT Book - Electricity: Circuits and their Components

 Page 1


Electricity: 
Circuits and their 
Components
3
Nihal and his classmates were excited for their school trip to the 
Bhakra Nangal Dam. There they would visit the hydroelectric 
power house where the force of falling water was used to generate 
electricity. They also looked forward to the free 13 kilometre- 
train ride from Nangal in Punjab to Bhakra in Himachal Pradesh, 
along the beautiful Sutlej river and through the Shivalik hills.
Prior to the trip, Nihal and his classmates were given a group 
assignment to prepare a presentation on the uses of electricity. 
They began by looking around their houses, then their school, 
followed by their neighbourhood, their city, and ? nally they 
searched the internet. To their astonishment, their list kept 
growing. They decided to organise the uses under di? erent 
headings.
Entertainment
Television, 
radio, 
_______________
Communication
Mobile phone, 
Internet, 
_______________
Others
Water pump, 
crane, computer, 
_______________
Lighting
Homes, o?  ces, 
streets, markets,  
factories,
_______________
Cooking
Electric kettle, mixer 
grinder, toaster, 
oven, microwave, 
_______________
Transportation
Train, bus, 
car, scooter, 
lift, escalator, 
_______________
Heating and Cooling
Fan, room heater, 
immersion rod, geyser, 
refrigerator, air 
conditioner, _____
Chapter 3.indd   23 4/3/2025   4:51:22 PM
Page 2


Electricity: 
Circuits and their 
Components
3
Nihal and his classmates were excited for their school trip to the 
Bhakra Nangal Dam. There they would visit the hydroelectric 
power house where the force of falling water was used to generate 
electricity. They also looked forward to the free 13 kilometre- 
train ride from Nangal in Punjab to Bhakra in Himachal Pradesh, 
along the beautiful Sutlej river and through the Shivalik hills.
Prior to the trip, Nihal and his classmates were given a group 
assignment to prepare a presentation on the uses of electricity. 
They began by looking around their houses, then their school, 
followed by their neighbourhood, their city, and ? nally they 
searched the internet. To their astonishment, their list kept 
growing. They decided to organise the uses under di? erent 
headings.
Entertainment
Television, 
radio, 
_______________
Communication
Mobile phone, 
Internet, 
_______________
Others
Water pump, 
crane, computer, 
_______________
Lighting
Homes, o?  ces, 
streets, markets,  
factories,
_______________
Cooking
Electric kettle, mixer 
grinder, toaster, 
oven, microwave, 
_______________
Transportation
Train, bus, 
car, scooter, 
lift, escalator, 
_______________
Heating and Cooling
Fan, room heater, 
immersion rod, geyser, 
refrigerator, air 
conditioner, _____
Chapter 3.indd   23 4/3/2025   4:51:22 PM
Curiosity | Textbook of Science | Grade 7
24
Can you help Nihal by adding some more uses to his lists? 
Also, suggest some other ways of grouping the uses of electricity.
We use electricity all the time, so let us learn something more 
about electricity. You have learnt earlier that electricity is 
generated in multiple ways?—?by windmills, by using wind 
energy, by solar panels capturing the Sun’s energy, by falling 
water and by using natural gas or coal (in the chapter ‘Nature’s 
Treasures’ in the Grade 6 Science textbook Curiosity). The electric 
supply from these sources reaches our homes and factories via 
wires. For example, at home we plug in various devices to the 
electrical sockets in the wall. However, to learn about electricity, 
we will focus on a portable source of electricity that most of us 
may have used. Let us start with its use in a common device like 
a torchlight.
Caution —?The danger signs on electric poles and 
other appliances warn people that electricity can 
be dangerous if not carefully handled. Never ever 
perform experiments with power supply at your 
home or school. Even electricity from portable 
generators can be dangerous. Use only batteries or 
cells, like those in torchlights, wall clocks, radios, or 
remotes, for experiments with electricity.
3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight
You might have used a torchlight, also called a torch or a ? ashlight.
Activity 3.1: Let us explore
? Take a torchlight similar to the one shown in Fig. 3.1.
? Observe it carefully. Do you notice a lamp? And a switch?
? Slide its switch and observe. Does the torch lamp glow?
? Now slide the switch back to its original position and observe 
the torch lamp.
You might have noticed that in the ? rst position of the switch, 
the torch lamp glows and in the other position the lamp does not 
glow.
? Now, open the torchlight. What do you ? nd inside?
Inside the torchlight, you may ? nd two or more electric cells. 
Why does the torch lamp 
glow in one position of 
its switch?
Fig. 3.1: A torchlight
Chapter 3.indd   24 4/3/2025   4:51:23 PM
Page 3


Electricity: 
Circuits and their 
Components
3
Nihal and his classmates were excited for their school trip to the 
Bhakra Nangal Dam. There they would visit the hydroelectric 
power house where the force of falling water was used to generate 
electricity. They also looked forward to the free 13 kilometre- 
train ride from Nangal in Punjab to Bhakra in Himachal Pradesh, 
along the beautiful Sutlej river and through the Shivalik hills.
Prior to the trip, Nihal and his classmates were given a group 
assignment to prepare a presentation on the uses of electricity. 
They began by looking around their houses, then their school, 
followed by their neighbourhood, their city, and ? nally they 
searched the internet. To their astonishment, their list kept 
growing. They decided to organise the uses under di? erent 
headings.
Entertainment
Television, 
radio, 
_______________
Communication
Mobile phone, 
Internet, 
_______________
Others
Water pump, 
crane, computer, 
_______________
Lighting
Homes, o?  ces, 
streets, markets,  
factories,
_______________
Cooking
Electric kettle, mixer 
grinder, toaster, 
oven, microwave, 
_______________
Transportation
Train, bus, 
car, scooter, 
lift, escalator, 
_______________
Heating and Cooling
Fan, room heater, 
immersion rod, geyser, 
refrigerator, air 
conditioner, _____
Chapter 3.indd   23 4/3/2025   4:51:22 PM
Curiosity | Textbook of Science | Grade 7
24
Can you help Nihal by adding some more uses to his lists? 
Also, suggest some other ways of grouping the uses of electricity.
We use electricity all the time, so let us learn something more 
about electricity. You have learnt earlier that electricity is 
generated in multiple ways?—?by windmills, by using wind 
energy, by solar panels capturing the Sun’s energy, by falling 
water and by using natural gas or coal (in the chapter ‘Nature’s 
Treasures’ in the Grade 6 Science textbook Curiosity). The electric 
supply from these sources reaches our homes and factories via 
wires. For example, at home we plug in various devices to the 
electrical sockets in the wall. However, to learn about electricity, 
we will focus on a portable source of electricity that most of us 
may have used. Let us start with its use in a common device like 
a torchlight.
Caution —?The danger signs on electric poles and 
other appliances warn people that electricity can 
be dangerous if not carefully handled. Never ever 
perform experiments with power supply at your 
home or school. Even electricity from portable 
generators can be dangerous. Use only batteries or 
cells, like those in torchlights, wall clocks, radios, or 
remotes, for experiments with electricity.
3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight
You might have used a torchlight, also called a torch or a ? ashlight.
Activity 3.1: Let us explore
? Take a torchlight similar to the one shown in Fig. 3.1.
? Observe it carefully. Do you notice a lamp? And a switch?
? Slide its switch and observe. Does the torch lamp glow?
? Now slide the switch back to its original position and observe 
the torch lamp.
You might have noticed that in the ? rst position of the switch, 
the torch lamp glows and in the other position the lamp does not 
glow.
? Now, open the torchlight. What do you ? nd inside?
Inside the torchlight, you may ? nd two or more electric cells. 
Why does the torch lamp 
glow in one position of 
its switch?
Fig. 3.1: A torchlight
Chapter 3.indd   24 4/3/2025   4:51:23 PM
Electricity: Circuits and their Components
25
3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit
To understand how a torch works, let us ? rst ? nd out about its 
components.
3.2.1 Electric cell
Activity 3.2: Let us observe
? Take an electric cell, turn it around and look at 
it carefully (Fig. 3.2). Do you notice a positive 
(+) sign and a negative (–) sign marked on the 
electric cell? Do you also notice that it has a 
small protruding metal cap on one side and a 
? at metal disc on the other side?
All electric cells have two terminals; one is called positive (+?ve) 
while the other is negative (–?ve). The metal cap is the positive
terminal of the electric cell and the metal disc is the negative
terminal. The electric cell is a portable source of electrical energy .
3.2.2 Battery
Activity 3.3: Let us experiment
? Take a torch which uses two cells. Open its cell compartment 
and take out the cells.
? Put the cells back in a di? erent order. Also, try reversing 
the direction of one cell. Then, slide the switch and check 
whether the lamp glows in each case. 
? Check the order in which the cells were placed in the torch 
when the lamp glows. 
The lamp glows when the cells are placed in the order as 
shown in Fig. 3.3. Notice how the terminals of the two cells are 
connected. The positive terminal of one cell is connected to the 
negative terminal of the next cell. Such a combination of two or 
more cells is called a battery. 
(a)
(b)
Fig. 3.3: A battery made up of (a) two cells (b) four cells
Fig. 3.2: An electric cell
Positive 
terminal
Negative 
terminal
In a torch, we generally 
use more than one cell. 
Are those placed in any 
particular order?
Chapter 3.indd   25 4/3/2025   4:51:26 PM
Page 4


Electricity: 
Circuits and their 
Components
3
Nihal and his classmates were excited for their school trip to the 
Bhakra Nangal Dam. There they would visit the hydroelectric 
power house where the force of falling water was used to generate 
electricity. They also looked forward to the free 13 kilometre- 
train ride from Nangal in Punjab to Bhakra in Himachal Pradesh, 
along the beautiful Sutlej river and through the Shivalik hills.
Prior to the trip, Nihal and his classmates were given a group 
assignment to prepare a presentation on the uses of electricity. 
They began by looking around their houses, then their school, 
followed by their neighbourhood, their city, and ? nally they 
searched the internet. To their astonishment, their list kept 
growing. They decided to organise the uses under di? erent 
headings.
Entertainment
Television, 
radio, 
_______________
Communication
Mobile phone, 
Internet, 
_______________
Others
Water pump, 
crane, computer, 
_______________
Lighting
Homes, o?  ces, 
streets, markets,  
factories,
_______________
Cooking
Electric kettle, mixer 
grinder, toaster, 
oven, microwave, 
_______________
Transportation
Train, bus, 
car, scooter, 
lift, escalator, 
_______________
Heating and Cooling
Fan, room heater, 
immersion rod, geyser, 
refrigerator, air 
conditioner, _____
Chapter 3.indd   23 4/3/2025   4:51:22 PM
Curiosity | Textbook of Science | Grade 7
24
Can you help Nihal by adding some more uses to his lists? 
Also, suggest some other ways of grouping the uses of electricity.
We use electricity all the time, so let us learn something more 
about electricity. You have learnt earlier that electricity is 
generated in multiple ways?—?by windmills, by using wind 
energy, by solar panels capturing the Sun’s energy, by falling 
water and by using natural gas or coal (in the chapter ‘Nature’s 
Treasures’ in the Grade 6 Science textbook Curiosity). The electric 
supply from these sources reaches our homes and factories via 
wires. For example, at home we plug in various devices to the 
electrical sockets in the wall. However, to learn about electricity, 
we will focus on a portable source of electricity that most of us 
may have used. Let us start with its use in a common device like 
a torchlight.
Caution —?The danger signs on electric poles and 
other appliances warn people that electricity can 
be dangerous if not carefully handled. Never ever 
perform experiments with power supply at your 
home or school. Even electricity from portable 
generators can be dangerous. Use only batteries or 
cells, like those in torchlights, wall clocks, radios, or 
remotes, for experiments with electricity.
3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight
You might have used a torchlight, also called a torch or a ? ashlight.
Activity 3.1: Let us explore
? Take a torchlight similar to the one shown in Fig. 3.1.
? Observe it carefully. Do you notice a lamp? And a switch?
? Slide its switch and observe. Does the torch lamp glow?
? Now slide the switch back to its original position and observe 
the torch lamp.
You might have noticed that in the ? rst position of the switch, 
the torch lamp glows and in the other position the lamp does not 
glow.
? Now, open the torchlight. What do you ? nd inside?
Inside the torchlight, you may ? nd two or more electric cells. 
Why does the torch lamp 
glow in one position of 
its switch?
Fig. 3.1: A torchlight
Chapter 3.indd   24 4/3/2025   4:51:23 PM
Electricity: Circuits and their Components
25
3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit
To understand how a torch works, let us ? rst ? nd out about its 
components.
3.2.1 Electric cell
Activity 3.2: Let us observe
? Take an electric cell, turn it around and look at 
it carefully (Fig. 3.2). Do you notice a positive 
(+) sign and a negative (–) sign marked on the 
electric cell? Do you also notice that it has a 
small protruding metal cap on one side and a 
? at metal disc on the other side?
All electric cells have two terminals; one is called positive (+?ve) 
while the other is negative (–?ve). The metal cap is the positive
terminal of the electric cell and the metal disc is the negative
terminal. The electric cell is a portable source of electrical energy .
3.2.2 Battery
Activity 3.3: Let us experiment
? Take a torch which uses two cells. Open its cell compartment 
and take out the cells.
? Put the cells back in a di? erent order. Also, try reversing 
the direction of one cell. Then, slide the switch and check 
whether the lamp glows in each case. 
? Check the order in which the cells were placed in the torch 
when the lamp glows. 
The lamp glows when the cells are placed in the order as 
shown in Fig. 3.3. Notice how the terminals of the two cells are 
connected. The positive terminal of one cell is connected to the 
negative terminal of the next cell. Such a combination of two or 
more cells is called a battery. 
(a)
(b)
Fig. 3.3: A battery made up of (a) two cells (b) four cells
Fig. 3.2: An electric cell
Positive 
terminal
Negative 
terminal
In a torch, we generally 
use more than one cell. 
Are those placed in any 
particular order?
Chapter 3.indd   25 4/3/2025   4:51:26 PM
Curiosity | Textbook of Science | Grade 7
26
Fig. 3.4: (a) A small incandescent 
lamp used in a torch (b) its 
simpli? ed drawing showing 
the connection of wires to the 
terminals
However, my torch has a 
di? erent kind of lamp. In fact, it 
cannot be taken out of the torch 
as it is ? xed in it. 
(b)
For many devices, we may need more than one cell. So, 
we connect two or more cells together as shown in Fig. 3.3. 
Connecting more than one cell provides energy to the circuit for 
a longer time and/or more energy. 
FASCINATING FACTS
The term battery is also used for a single cell. We use the term battery 
even for the single cell that powers our mobile phones.
3.2.3 Electric lamp
Incandescent Lamp
Activity 3.4: Let us observe
(a)
Glass bulb
Thick 
wire
Insulator 
(support)
Insulator 
Filament
Thick 
wire
Metal case 
(other 
terminal)
Metal tip
(one terminal)
Metal case 
terminal)
For this activity, you will require a torchlight with an 
incandescent lamp (or light bulb). Many old torchlights 
still use such lamps. With your teacher’s help, con? rm 
that your torchlight uses an incandescent lamp.
? Take the torch and examine its lamp. What do you 
see? Do you notice a thin wire ? xed in the middle 
of the glass bulb? 
? Now, switch on the torch. Which part of the lamp 
glows? 
The thin wire inside the glass bulb of the lamp glows. 
The glowing thin wire is called the ? lament of the lamp. 
? Take out the lamp with the help of your teacher and 
inspect it from all sides. How is the ? lament ? xed?
The ? lament is attached to two thicker wires that 
support it, as shown in Fig. 3.4a. One thick wire connects 
to the metal case at the lamp’s base, while the other 
connects to the metal tip at the centre of the base (Fig. 
3.4b). These form the two terminals of the lamp, and 
are ? xed in a way that they do not touch each other. 
In such incandescent lamps, the ? lament gets hot and 
glows to produce light. 
Chapter 3.indd   26 4/3/2025   4:51:27 PM
Page 5


Electricity: 
Circuits and their 
Components
3
Nihal and his classmates were excited for their school trip to the 
Bhakra Nangal Dam. There they would visit the hydroelectric 
power house where the force of falling water was used to generate 
electricity. They also looked forward to the free 13 kilometre- 
train ride from Nangal in Punjab to Bhakra in Himachal Pradesh, 
along the beautiful Sutlej river and through the Shivalik hills.
Prior to the trip, Nihal and his classmates were given a group 
assignment to prepare a presentation on the uses of electricity. 
They began by looking around their houses, then their school, 
followed by their neighbourhood, their city, and ? nally they 
searched the internet. To their astonishment, their list kept 
growing. They decided to organise the uses under di? erent 
headings.
Entertainment
Television, 
radio, 
_______________
Communication
Mobile phone, 
Internet, 
_______________
Others
Water pump, 
crane, computer, 
_______________
Lighting
Homes, o?  ces, 
streets, markets,  
factories,
_______________
Cooking
Electric kettle, mixer 
grinder, toaster, 
oven, microwave, 
_______________
Transportation
Train, bus, 
car, scooter, 
lift, escalator, 
_______________
Heating and Cooling
Fan, room heater, 
immersion rod, geyser, 
refrigerator, air 
conditioner, _____
Chapter 3.indd   23 4/3/2025   4:51:22 PM
Curiosity | Textbook of Science | Grade 7
24
Can you help Nihal by adding some more uses to his lists? 
Also, suggest some other ways of grouping the uses of electricity.
We use electricity all the time, so let us learn something more 
about electricity. You have learnt earlier that electricity is 
generated in multiple ways?—?by windmills, by using wind 
energy, by solar panels capturing the Sun’s energy, by falling 
water and by using natural gas or coal (in the chapter ‘Nature’s 
Treasures’ in the Grade 6 Science textbook Curiosity). The electric 
supply from these sources reaches our homes and factories via 
wires. For example, at home we plug in various devices to the 
electrical sockets in the wall. However, to learn about electricity, 
we will focus on a portable source of electricity that most of us 
may have used. Let us start with its use in a common device like 
a torchlight.
Caution —?The danger signs on electric poles and 
other appliances warn people that electricity can 
be dangerous if not carefully handled. Never ever 
perform experiments with power supply at your 
home or school. Even electricity from portable 
generators can be dangerous. Use only batteries or 
cells, like those in torchlights, wall clocks, radios, or 
remotes, for experiments with electricity.
3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight 3.1 A Torchlight
You might have used a torchlight, also called a torch or a ? ashlight.
Activity 3.1: Let us explore
? Take a torchlight similar to the one shown in Fig. 3.1.
? Observe it carefully. Do you notice a lamp? And a switch?
? Slide its switch and observe. Does the torch lamp glow?
? Now slide the switch back to its original position and observe 
the torch lamp.
You might have noticed that in the ? rst position of the switch, 
the torch lamp glows and in the other position the lamp does not 
glow.
? Now, open the torchlight. What do you ? nd inside?
Inside the torchlight, you may ? nd two or more electric cells. 
Why does the torch lamp 
glow in one position of 
its switch?
Fig. 3.1: A torchlight
Chapter 3.indd   24 4/3/2025   4:51:23 PM
Electricity: Circuits and their Components
25
3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit 3.2 A Simple Electrical Circuit
To understand how a torch works, let us ? rst ? nd out about its 
components.
3.2.1 Electric cell
Activity 3.2: Let us observe
? Take an electric cell, turn it around and look at 
it carefully (Fig. 3.2). Do you notice a positive 
(+) sign and a negative (–) sign marked on the 
electric cell? Do you also notice that it has a 
small protruding metal cap on one side and a 
? at metal disc on the other side?
All electric cells have two terminals; one is called positive (+?ve) 
while the other is negative (–?ve). The metal cap is the positive
terminal of the electric cell and the metal disc is the negative
terminal. The electric cell is a portable source of electrical energy .
3.2.2 Battery
Activity 3.3: Let us experiment
? Take a torch which uses two cells. Open its cell compartment 
and take out the cells.
? Put the cells back in a di? erent order. Also, try reversing 
the direction of one cell. Then, slide the switch and check 
whether the lamp glows in each case. 
? Check the order in which the cells were placed in the torch 
when the lamp glows. 
The lamp glows when the cells are placed in the order as 
shown in Fig. 3.3. Notice how the terminals of the two cells are 
connected. The positive terminal of one cell is connected to the 
negative terminal of the next cell. Such a combination of two or 
more cells is called a battery. 
(a)
(b)
Fig. 3.3: A battery made up of (a) two cells (b) four cells
Fig. 3.2: An electric cell
Positive 
terminal
Negative 
terminal
In a torch, we generally 
use more than one cell. 
Are those placed in any 
particular order?
Chapter 3.indd   25 4/3/2025   4:51:26 PM
Curiosity | Textbook of Science | Grade 7
26
Fig. 3.4: (a) A small incandescent 
lamp used in a torch (b) its 
simpli? ed drawing showing 
the connection of wires to the 
terminals
However, my torch has a 
di? erent kind of lamp. In fact, it 
cannot be taken out of the torch 
as it is ? xed in it. 
(b)
For many devices, we may need more than one cell. So, 
we connect two or more cells together as shown in Fig. 3.3. 
Connecting more than one cell provides energy to the circuit for 
a longer time and/or more energy. 
FASCINATING FACTS
The term battery is also used for a single cell. We use the term battery 
even for the single cell that powers our mobile phones.
3.2.3 Electric lamp
Incandescent Lamp
Activity 3.4: Let us observe
(a)
Glass bulb
Thick 
wire
Insulator 
(support)
Insulator 
Filament
Thick 
wire
Metal case 
(other 
terminal)
Metal tip
(one terminal)
Metal case 
terminal)
For this activity, you will require a torchlight with an 
incandescent lamp (or light bulb). Many old torchlights 
still use such lamps. With your teacher’s help, con? rm 
that your torchlight uses an incandescent lamp.
? Take the torch and examine its lamp. What do you 
see? Do you notice a thin wire ? xed in the middle 
of the glass bulb? 
? Now, switch on the torch. Which part of the lamp 
glows? 
The thin wire inside the glass bulb of the lamp glows. 
The glowing thin wire is called the ? lament of the lamp. 
? Take out the lamp with the help of your teacher and 
inspect it from all sides. How is the ? lament ? xed?
The ? lament is attached to two thicker wires that 
support it, as shown in Fig. 3.4a. One thick wire connects 
to the metal case at the lamp’s base, while the other 
connects to the metal tip at the centre of the base (Fig. 
3.4b). These form the two terminals of the lamp, and 
are ? xed in a way that they do not touch each other. 
In such incandescent lamps, the ? lament gets hot and 
glows to produce light. 
Chapter 3.indd   26 4/3/2025   4:51:27 PM
Electricity: Circuits and their Components
27
Fig. 3.6: LEDs of different colours
+
- + + +
+
- - - -
LED Lamp
Many torches in use today have a Light Emitting Diode (LED) lamp, 
instead of an incandescent lamp, as shown in Fig. 3.5. 
Fig. 3.5: An LED lamp for torch
LED lamp
Fig. 3.5: An LED lamp for torch
Activity 3.5: Let us observe
? Take an LED of any colour (Fig. 3.6) and 
observe. Do you see any ? lament inside it?
? Notice the length of two wires attached to 
the LED. Do you ? nd one of those longer 
than the other?
Unlike incandescent lamps, LEDs do not 
have ? laments (Fig. 3.6). They also have two 
terminals, but one is positive (attached to a 
longer wire) and the other is negative (the 
shorter wire). A torch may use one or more 
LEDs, sometimes of di? erent shapes, in its 
lamp.
After having learnt about the electric cell, battery, and electric 
lamps, we are now ready to make the torch lamp glow using an 
electric cell or battery.
3.2.4 Making an electric lamp glow using an 
electric cell or battery
Activity 3.6: Let us construct
? Take an electric cell, an incandescent lamp used in a torch, a 
cell holder, a lamp holder, and four lengths of electric wire.
? Remove about 1 cm of the plastic covering from both ends of 
each wire to expose the metal.
? Attach two wires to the two ends of the cell holder as shown 
in Fig. 3.7a.
Chapter 3.indd   27 4/3/2025   4:51:28 PM