These NCERT Solutions for Class 6 Science Chapter 12 Electricity and Circuits Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.
Electricity and Circuits NCERT Solutions for Class 6 Science Chapter 12
Class 6 Science Chapter 12 Electricity and Circuits Textbook Exercise Questions and Answers
Fill in the blanks:
a. A device that is used to break an electric circuit is called ………………….
b. An electric cell has …………………. terminals.
Mark ‘True’ or ‘False’ for the following statements:
a. Electric current can flow through metals.
b. Instead of metal wires, a jute string can be used to make a circuit.
c. Electric current can pass through a sheet of thermocol.
Explain why the bulb would not glow in the arrangement shown in the given figure.
The bulb would not glow because one end of the tester/screwdriver is made up of plastic which does not allow the electric current to flow through it.
Complete the drawing shown in figure to indicate where the free ends of the two wires should be joined to make the bulb glow.
What is the purpose of using an electric switch? Name some electrical gadgets that have switches built into them.
An electrical switch is used to open the circuit or to close the circuit due to which electrical gadgets start or stop. Electrical switch is used in many electrical gadgets such as: television, washing machine, electrical mixer, toaster, heater, etc.
Would the bulb glow after completing the circuit shown in figure of Question 4, if instead of safety pin we use an eraser?
No, since eraser is an insulator so it does not allow the current to pass through it. Hence, the bulb will not glow.
Would the bulb glow in the circuit shown in the given figure?
No, the electric bulb has two terminals and both the wires are connected to one terminal of the bulb. Current will not flow from the bulb and it will not glow. To make it glow, we have to connect one wire to each terminal of the bulb.
Using the “conduction tester” on an object it was found that the bulb begins to glow. Is that object a conductor or an insulator? Explain.
If the object is a good conductor of electricity, then current will pass through conduction tester and the bulb will glow. Hence, the object will be a conductor of electricity.
Why should an electrician use rubber gloves while repairing an electric switch at your home? Explain.
Our body is a good conductor of electricity and rubber is an insulator. During repairing work, if the body comes in contact with current carrying wire then there will not be any accident as rubber does not allow the passage of current through it. Hence, electrician should use rubber gloves while repairing an electric switch.
The handles of the tools like screwdrivers and pliers used by electricians for repair work usually have plastic or rubber covers on them. Can you explain why?
Plastic or rubber is an insulator which does not allow electric current to pass through it. The handles of the tools like screwdrivers and pliers used by electricians for repair have covering of plastic or rubber so that electric current may not pass through these tools to the body of the electrician to harm him.
NCERT Extended Learning Activities And Projects
Imagine there were no electric supply for a month. How would that affect your day-to-day activities and others in your family? Present your imagination in the form of a story or a play. If possible stage the play written by you or your friends in school.
Do it yourself.
For your friends, you may set up a game “How steady is your hand?”. You will need a cell, an electric bulb, a metal key, two iron nails (about 5 cm in length), about one and a half metre long thick metal wire (with its plastic insulation scraped off) and few pieces of connecting wires. Fix two nails nearly one metre apart on a wooden board so that these can be used as a hook. Fix the wire between the nails after inserting it through the loop of the key. Connect one end of this wire to a bulb and a cell. Connect the other terminal of the cell to the key with a wire. Ask your friend to move the loop along the straight wire without touching it. Glowing of the bulb would indicate that the loop of the key has touched the wire.
Do it yourself.
Read and find out about Alessandro Volta who invented the electric cell. You may also find out about Thomas Alva Edison who invented the electric bulb.
Do it yourself.
Objective: To make an electric bulb light up
using an electric cell.
Materials Required: Bulb, cell and connecting wire.
- Take four lengths of electric wire with differently coloured plastic coverings.
- Remove a little of the plastic covering from each length of wire at the ends. This would expose the metal wires at the ends of each length.
- Fix the exposed parts of the wires to the cell and the bulb as shown in figure below.
- You can stick the wires to the bulb with the tape used by electricians. Use rubber bands or tape to fix the wires to the cell.
- Now, connect the wires fixed to the bulb with those attached to the cell in six different ways as has been shown below. For each arrangement, find out whether the bulb glows or not.
Observations: You connected one terminal of the electric cell to the other terminal through wires passing to and from the electric bulb. Note that in the arrangements shown in Fig. (a) and (f), the two terminals of the electric cell were connected to the two terminals of the bulb. Such an arrangement is an example of a closed electric circuit.
Conclusion: The electric circuit provides a complete path for electricity to pass (current to flow) between the two terminals of the electric cell. The bulb glows only when current flows through the circuit.
- Electric bulb: Electric bulb is the electrical device which converts electrical energy into light and heat energy.
- Filament: Filament is a thin wire in the bulb which is made up of tungsten metal and is used to emit light in the bulb. The Filament gets heated due to electric current. This heat is then converted into light.
Objective: To study the structure of a torch bulb.
Material Required: A torch bulb.
- Take out the bulb from a torch.
- Observe the bulb from outside and also from inside with a magnifying glass.
- List the various parts you could see.
Observations: The torch bulb consists of the following parts:
- Metal casing having grooves in the lower part.
- A small spiral of thin wire called filament is present.
- Two slightly thicker wires in the upper ends of the wires support the filament.
- The lower end of the one of the thicker wire is connected to the metal casing and that of the other wire to the metal tip at the bottom of the bulb.
- The metal tip and the metal casing are fixed in such a way that they do not touch each other.
Electric switch: Electric switch is a device by which an electric circuit can be easily completed or broken. The switch is ‘ON’ in a closed circuit and ‘OFF’ in an open circuit.
Objective: To make a simple and easy switch to use in our circuit.
Materials Required: Two drawing pins, a safety pin (or a paper clip), two wires and a small sheet of thermocol or a wooden board.
- Insert a drawing pin into the ring at one end of the safety pin and fix it on the thermocol sheet as shown in the figure.
- Make sure that the safety pin can be rotated freely.
- Now, fix the other drawing pin on the thermocol sheet in a way that the free end of the safety pin can touch it.
- The safety pin fixed in this way would be your switch in this activity.
- Now, make a circuit by connecting an electric cell and a bulb with this switch as shown. Rotate the safety pin so that its free end touches the other drawing pin and observe.
- Now, move the safety pin away and observe again.
- The safety pin covered the gap between the drawing pins when you made it touch the two of them. In this position the switch is said to be ‘on’. Since the material of the safety pin allows the current to pass through it, the circuit was complete. Hence, the bulb glows.
- On the other hand, the bulb did not glow when the safety pin was not in touch with the other drawing pin. The circuit was not complete as there was a gap between the two drawing pins. In this position, the switch is said to be ‘off’.
Conductors: Conductors are the materials which allow the electric current to pass through them. Mostly metals are good conductors of electricity.
Insulators: Insulators are the materials which do not allow the electric current to pass through them. Rubber and wood are insulators.
Objective: To find out which object is a conductor and which is an insulator.
Materials Required: Three pieces of wire, a small torch bulb, a thick sheet of cardboard or wood, sticky tape, pencil cell and objects such as metal spoon, eraser, peel of wood, etc. Procedure:
- Connect a pencil cell to the socket which holds a small torch bulb.
- Attach clips to the bare ends of both wires.
- Hold various objects between the two clips.
- Observe if the bulb glows or not. Record your observations.
- The bulb does not glow when the free ends of the wires are in contact with some of the materials you have tested. This means that these materials do not allow the electric current to pass through them.
- On the other hand, some materials allow electric current to pass through them, which is indicated by the glowing bulb.
Materials which allow electric current to pass through them are conductors of electricity. Insulators do not allow electric current to pass through them.
Class 6 Science Chapter 12 Electricity and Circuits Additional Important Questions and Answers
Very Short Answer Type Questions
How much voltage is given by a single dry cell?
Name the two types of circuits.
Open circuit and closed circuit are the two types of circuits.
Name two terminals that all electric cells contain.
Positive terminal and negative terminal.
What is the work of an electric cell?
An electric cell converts chemical energy into electrical energy.
The combination of two or more than two cells is called a battery.
What is the work of a filament in a bulb?
A filament gets heated and emits light in the bulb.
What is a solar cell?
A solar cell is a device which converts solar energy into electrical energy.
Write one use of insulators.
Insulators are used in making switchboards, handles of testers, screwdrivers, etc.
Name a device which is used to ‘open’ or ‘close’ a circuit.
How does an electric cell produce electricity?
An electric cell produces electricity from chemicals stored inside it.
Is electricity pollution free and a useful form of energy?
Which terminal of the cell does have a metal cap?
In a cell, the carbon rod is surrounded by which mixture?
Manganese dioxide and powdered charcoal.
Short Answer Type Questions
Write two advantages of a dry cell.
Two advantages of a dry cell are:
- It converts chemical energy into electrical energy.
- It is light in weight and small in
What is the difference between a conductor and an insulator?
A conductor allows the passage of current through it whereas an insulator does not allow the passage of current through it.
How does a bulb start glowing with an electric cell?
When the electric cell is connected with conducting wire and the wire ends are connected to the bulb, the bulb glows immediately.
If you touch an electric wire carrying current you get a shock, but if on the same wire, the birds sit they do not get any shock/current. Give reason.
When we hold the wire carrying current then the circuit is closed and the current flows from our body and enters the earth but the birds sitting on the same wire do not get any current as the circuit is not complete. If the bird touches the earth wire, it will die due to electric shock.
What is a switch? When we switch on an electrical appliance, what changes are we making to the circuit?
The switch is a simple device which is used to open or close a circuit. When the switch is turned on, the gap in the circuit is closed and a complete circuit is made. Due to complete circuit, electricity starts flowing in the circuit and electrical appliance will now start working.
Draw a diagram showing a bulb connected to a dry cell making a closed circuit.
Describe the positive and negative terminals of a cell.
The metal cap of the cell is considered as positive terminal. It is indicated by sign (+). The metal disc or the container of the cell is the negative terminal. It is indicated by sign (-).
What is a fused bulb? Why it does not glow?
Bulb has a small filament inside it. If the filament of a bulb is broken, then such a bulb with broken filament is called fused bulb. The broken filament cannot complete the circuit. As a result, current cannot flow through the filament and fused bulb does not glow.
What are the essential components or elements of an electric circuit?
The essential components or elements of an electric circuit are:
- Electric sources (cell, battery).
- Electric appliances (a device for using the electric current).
- Conductor (for providing a path for the flow of current).
- Switch or key (for opening and closing the circuit).
Long Answer Type Questions
What is an electric circuit? Describe the various types of electric circuits with the help of diagrams.
The path along which electricity flows is called an electric circuit. There are two different types of electric circuits:
a. Closed circuit: The circuit in which electric current flows from one terminal of a cell or battery to the other is called a closed circuit.
b. Open circuit: The circuit in which electrical contact at any point is broken is called an open circuit. No current flows in an open circuit.
What is a torch? How does it work?
A torch is a portable electric lamp which uses two or more cells to light a small bulb. A torch contains a simple electric circuit. In a torch, two (or more) cells are connected to a torch bulb through a sliding switch. When the torch is needed to provide light, we close the sliding switch by pushing it forward so that the circuit is completed and the bulb lights up.
What are the differences between conductors and insulators?
|1. Those substances through which electricity can flow are called conductors.||1. Those substances through which electricity cannot flow are called insulators.|
|2. Electrical resistance of conductors is very low.||2. Electrical resistance of insulators is very high.|
|3. They contain large number of free electrons.||3. They do no contain free electrons.|
|4. Generally metals are conductors. E.g., silver, copper, aluminium.||4. Generally non-metals are insulators. E.g., wood, rubber, plastic.|
Define the following terms: (a) Dry cell and (b) Secondary cell.
a. Dry cell: An electric cell is used to operate objects like calculators and phones. It is a small source of electricity or electric current. It is also known as a pencil cell or dry cell. A dry cell has two terminals. One side that has a small circular metal cap is the positive terminal. It is marked with positive (+) sign. The other side has a flat metal plate behaves like the negative terminal and is marked with a negative (-) sign.
There are some chemicals inside a cell. These chemicals react to produce electricity. When the chemicals get used up, the cell stops producing electricity and the appliance stops functioning. These electric cells then . have to be replaced by new cells.
b. Secondary cell: Secondary cells are the cells that provide electrical energy to the gadget as a result of chemical reactions taking place in them. In these cells, electrical energy can be stored in the form of chemical energy and the stored chemical energy can be reconverted into electrical energy. Such cells are also called rechargeable cells. Lead accumulator and nickel- iron accumulators are two examples of secondary cells. They are mainly used in mobile phones, laptops and car batteries.
What is the importance of electricity in our life?
We use a variety of things in our day-to-day life that run on electricity such as fans, lights, televisions, radio, refrigerator and computer. Electricity makes it possible to light our homes, roads, offices, markets and factories even after sunset. This helps us to continue working at night. In the field of communication, electricity is also used as a medium for the transmission of signals. The different fields of our life which depend on electricity are rather wide.
Mention the precautions that are advised while handling electric appliances.
While handling electric appliances, the following precautions need to be taken.
- Do not operate an electric appliance or switch with wet hands.
- While using electric appliances, always wear rubber soled footwear. Rubber being a bad conductor of electricity prevents current from passing through our body.
- In case of a fire caused by electric spark, make sure that we should not throw water on electric appliances. Always use an extinguisher to put out electrical fires.
Observe the given circuits and tell in which of them will the bulb glow?
Bulb will glow in case (a) and (d).
a. Identify the objects A and B.
b. Which of them will conduct electricity?
c. Which of them is an insulator?
a. A-Rubber; B-Metal key.
b. Metal Key