Extra 20 important long questions and answers from Chapter:12 Electricity and Circuits of Class 6 Science (CBSE).
1. What is an electric circuit? Explain its components.
Answer:
An electric circuit is a closed path through which electric current flows. It consists of the following components:
Power Source
: Provides energy for the circuit (e.g., battery or cell).
Conducting Wires
: Allow electricity to flow between components.
Switch
: Opens or closes the circuit to control the flow of electricity.
Load (Bulb, Fan, etc.)
: The component that uses electrical energy.
Positive & Negative Terminals
: The two ends of the power source through which current flows.
Fuse (optional)
: A safety device that protects against excessive current.
2. What are conductors and insulators? Give examples of each.
Answer:
Conductors
: Materials that allow electricity to pass through them.
Examples: Copper,
Aluminium
, Iron, Silver.
Insulators
: Materials that do not allow electricity to pass through them.
Examples: Plastic, Rubber, Wood, Glass.
Conductors are used in electrical wiring, while insulators are used as coatings for wires.
Good conductors help in smooth electricity transmission, while insulators prevent electric shocks.
Both conductors and insulators play important roles in electrical safety.
3. What are the different types of electric circuits? Explain them.
Answer:
Electric circuits are of two types:
Open Circuit
: The circuit is incomplete, and electricity does not flow.
Closed Circuit
: The circuit is complete, and electricity flows properly.
Series Circuit
:
Components are connected one after another.
If one component fails, the entire circuit stops working.
Parallel Circuit
:
Components are connected separately to the power source.
If one component fails, others continue working.
Household Wiring
uses parallel circuits for efficiency.
4. Why is a switch important in an electric circuit?
Answer:
A switch is a device used to
open or close
an electric circuit.
When the switch is
ON
, the circuit is complete, and electricity flows.
When the switch is
OFF
, the circuit is broken, and electricity stops.
It helps in
controlling electrical appliances
safely.
Without a switch, we would have to disconnect wires to stop the flow of electricity.
Switches prevent
electrical hazards
and are used in homes, schools, and industries.
5. What is an electric cell? Explain its structure and working.
Answer:
An electric cell is a
device that generates electricity
using chemical energy.
It has
two terminals
: a
positive (+) metal cap
and a
negative (-) metal base
.
It contains a
chemical paste
that produces electricity.
The
chemical reaction
inside the cell creates
electric potential difference
.
When connected to a circuit, electrons flow, and the device works.
Common examples of electric cells include
AA batteries, AAA batteries, and button cells
.
6. How does an electric bulb work?
Answer:
An electric bulb has a
thin wire filament
inside it.
The filament is usually made of
tungsten
, a metal with high melting point.
When electric current passes through it, the filament gets
heated
and
glows
.
The bulb is filled with
inert gases
like argon to prevent the filament from burning.
The
base of the bulb
helps in connecting it to the circuit.
If the filament breaks, the circuit is open, and the bulb does not glow.
7. What are the advantages of parallel circuits over series circuits?
Answer:
In a
parallel circuit
, if one component stops working, others still function.
Each appliance receives the same voltage, ensuring proper working.
The brightness of bulbs does not reduce when more bulbs are added.
Parallel circuits are used in
household wiring
for better efficiency.
Each device can be turned on or off
independently
.
Parallel circuits prevent
overheating
and
voltage drop
.
8. How can we ensure safety while using electricity?
Answer:
Do not touch electrical appliances with
wet hands
.
Avoid inserting metal objects into
electrical sockets
.
Do not overload sockets with
too many appliances
.
Use
proper insulation
for wires to prevent shocks.
Always switch off electrical devices
when not in use
.
Use
fuses and circuit breakers
to prevent electrical fires.
9. What is the function of a fuse in an electric circuit?
Answer:
A
fuse
is a safety device used in electrical circuits.
It is made of a
thin wire
with a low melting point.
When excessive current flows, the fuse wire
melts
and breaks the circuit.
This prevents
damage to appliances
and reduces the risk of fire.
Fuses are commonly used in
household wiring, electrical devices, and industrial circuits
.
Modern electrical systems use
circuit breakers
instead of traditional fuses.
10. Why do electric shocks occur? How can they be prevented?
Answer:
Electric shocks occur when the
human body comes in direct contact with electricity
.
The body is a
good conductor
of electricity, so current flows through it.
Common causes include
faulty wiring, broken appliances, and wet conditions
.
Use
insulated tools
and
rubber gloves
while working with electricity.
Install
circuit breakers
to prevent electrical overloads.
Always turn off electrical appliances
before repairing them
.
11. What is the difference between a battery and a cell?
|
Feature |
Cell |
Battery |
|---|---|---|
|
Definition |
A single unit that generates electricity |
A combination of two or more cells |
|
Example |
AA cell, Button cell |
Car battery, Laptop battery |
|
Voltage |
Low (1.5V per cell) |
Higher (6V, 12V, etc.) |
|
Use |
Torches, Clocks |
Cars, UPS, Laptops |
12. Why do bulbs stop working after some time?
Answer:
The filament inside the bulb
burns out
after long use.
Repeated heating and cooling cause
wear and tear
.
Sudden
voltage fluctuations
may damage the filament.
Poor
quality bulbs
may have a shorter lifespan.
Excess
power supply
can cause overheating.
Replacing the bulb restores the circuit.
13. What is a short circuit? What are its causes and effects?
Answer:
A short circuit occurs when electric current flows through an unintended path, often causing damage.
Causes:
Damaged wires
– Exposed wires may touch each other.
Overloaded sockets
– Too many appliances in one socket can cause overheating.
Faulty electrical appliances
– Defective wiring can lead to short circuits.
Effects:
4. Can cause electrical fires and damage appliances.
5. May result in electric shocks if a person touches a faulty wire.
6. Fuse or circuit breaker trips, stopping the flow of electricity.
14. What are the main differences between open and closed circuits?
|
Feature |
Open Circuit |
Closed Circuit |
|---|---|---|
|
Definition |
A circuit where electricity cannot flow |
A circuit where electricity flows |
|
Switch Position |
OFF |
ON |
|
Bulb Glows? |
No |
Yes |
|
Example |
Wire disconnected from the battery |
Complete circuit with connected wires |
In an
open circuit
, there is a break in the path of electricity.
In a
closed circuit
, electricity flows continuously.
Electrical appliances work only in a
closed circuit
.
If a switch is turned off, the circuit becomes
open
.
15. Why is electrical wiring done using copper wires?
Answer:
Copper is a good conductor
– It allows electricity to pass easily.
Low resistance
– Prevents energy loss as heat.
Ductile and flexible
– Can be bent and shaped easily for wiring.
Durable and long-lasting
– Does not break easily.
Does not rust
– Copper remains functional for a long time.
Used in
household wiring, power transmission, and electronics
.
16. How does a torch work?
Answer:
A torch contains
batteries (cells)
as a power source.
When the
switch is pressed
, it
completes the circuit
.
Electricity flows
from the battery to the bulb.
The
bulb’s filament glows
, producing light.
A
reflector inside the torch
helps direct the light forward.
When the switch is released, the circuit opens, and the torch turns off.
17. What are the main precautions to follow while handling electrical appliances?
Answer:
Do not touch electrical appliances with wet hands.
Turn off switches before plugging or unplugging devices.
Do not overload sockets
by plugging in too many appliances.
Check for damaged wires
and replace them immediately.
Keep electrical devices away from water sources
like bathrooms.
Use proper earthing
to prevent electric shocks.
18. Why should we not connect a wire directly from the positive terminal to the negative terminal of a battery?
Answer:
Direct connection causes a
short circuit
.
The battery will
overheat
and may explode.
A large amount of
current flows instantly
, damaging the battery.
No useful work is done as no electrical device is connected.
It can cause
electric shocks
or fires.
Always connect batteries properly through a
load (like a bulb or motor)
.
19. How is electricity useful in our daily life?
Answer:
Lighting
– Electric bulbs and tube lights help us see in the dark.
Cooking
– Electric stoves, ovens, and microwaves use electricity.
Communication
– Televisions, computers, and mobile phones need electricity.
Transportation
– Electric trains and electric cars run on electricity.
Medical Equipment
– Hospitals use electric machines like X-rays and ventilators.
Industries
– Factories use electricity to operate machines.
20. What is an electric bell? Explain its working.
Answer:
An electric bell is a device that rings when electricity passes through it.
Parts of an electric bell:
Electromagnet
– A coil of wire that acts as a magnet when electricity flows.
Iron Armature
– A small metal strip that moves.
Hammer and Gong
– The hammer strikes the gong to produce sound.
Switch and Battery
– Supplies electricity to the circuit.
Working of an electric bell:
5. When the switch is turned ON, electricity flows, and the electromagnet attracts the armature.
6. The hammer strikes the gong, producing a ringing sound.
7. The circuit breaks and reconnects quickly, making the bell ring continuously.
