A(n) ___ can act as an electronic switch that opens or closes the circuits for electrical charges.

NCERT Solutions
Class 6
Science
electricity and circuits

NCERT Solutions for Class 6 Science Chapter 12 Electricity And Circuits are provided here with simple step-by-step explanations. These solutions for Electricity And Circuits are extremely popular among Class 6 students for Science Electricity And Circuits Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the NCERT Book of Class 6 Science Chapter 12 are provided here for you for free. You will also love the ad-free experience on Meritnation’s NCERT Solutions. All NCERT Solutions for class Class 6 Science are prepared by experts and are 100% accurate.

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What can act as an electronic switch that opens or closes the circuits for electrical charges?
What can act as an electronic switch?
Can a diode act as a switch?
How does pn junction diode act as a switch?

Page No 160:

Question A:

Solve the following crossword puzzle:
Figure

Across
2. The coil inside an electric bulb
3. It allows the flow of current

Down
1. The best conductor of electricity
3. A small source of current
4. It is used to open or close the circuit

Answer:

Page No 160:

Question B.1:

If current is drawn from the cell, the circuit is said to be
(a) open
(b) complete
(c) magnetised
(d) fused

Answer:

(b) complete
When a circuit is complete, current is drawn from a cell.

Page No 160:

Question B.2:

The closed path in which the current flows is called a/an
(a) electric circuit
(b) switch
(c) conductor
(d) cell

Answer:

(a) electric circuit
An electric circuit is one which consists of a cell, a switch, a conductor and an electrical device. When the circuit is complete, current flows through it.

Page No 160:

Question B.3:

In a primary cell, the chemical energy is converted into
(a) electrical energy
(b) sound energy
(c) mechanical energy
(d) light energy

Answer:

(a) electrical energy
A primary cell converts chemical energy into electrical energy.

Page No 160:

Question B.4:

Which of the following uses a chemical reaction to produce an electric current?
(a) dry cell
(b) windmill
(c) steam engine
(d) bulb

Answer:

(a) dry cell
Chemical reaction takes place inside a dry cell to produce electrical current.

Page No 160:

Question B.5:

An electric switch is also sometimes referred to as a
(a) circuit
(b) key
(c) cell
(d) battery

Answer:

(b) key
The key of an electric circuit is also known as switch.

Page No 160:

Question B.6:

The device used to open or close an electric circuit is called a/an
(a) cell
(b) electric circuit
(c) electric switch
(d) battery

Answer:

Page No 160:

Question B.7:

Which of these appliances in your house is not run by electricity?
(a) geyser
(b) gas burner
(c) air conditioner
(d) music system

Answer:

(b) gas burner
Gas burner uses gas, not electricity.

Page No 161:

Question C:

Write True (T) or False (F) against the following statements in the given brackets:
1. Electricity in motion is called current electricity. ( )
2. Rubber is a good example of electric insulator. ( )
3. The base of an electric cell is its negative terminal. ( )
4. The supporting wire breaks in a fused bulb. ( )
5. Electric current can flow through metals. ( )
6. An electric cell two terminals. ( )
7. An electric bulb has a filament that is connected to its terminals. ( )
8. Instead of metal wires, a jute string can be used to make a circuit. ( )

Answer:

1. True (T)

2. True (T)

3. True (T)

4. True (T)

5. True (T)

6. True (T)

7. True (T)

8. False (F)
Jute is an insulator; hence, it cannot be used in an electric circuit.

Page No 161:

Question D:

Figures below show a cell connected to a bulb through insulate copper wires. State with a reason in which case the bulb will glow and not glow:

Figure

Answer:

(b)
All the circuits except the one in Option (b) are open; therefore, only (b) will allow the flow of current.

Page No 161:

Question E:

Figures below show a cell connected to a bulb different types of material. State with a reason in which case the bulb will glow and not glow:

Figure

Answer:

(a) The bulb will not glow. This is because the rubber band is an insulator and the circuit is incomplete.

(b) The bulb will not glow because jute and silk threads don't conduct electricity.

(c) The bulb will glow in this case, as the circuit is completed by the copper wire, which is a good conductor of electricity.

(d) The bulb will not glow because the circuit is open.

(e) The bulb will not glow, as cotton does not conduct electricity.

(f) The bulb will not glow because of the plastic piece which is an insulator.

Page No 162:

Question 1:

Using the 'Conduction Tester' on a object, it was found that the bulb begins to glow. Is that object a conductor an insulator? Explain.

Answer:

The object is a conductor because when the tester is touched to it, the bulb starts glowing indicating the flow of current. Since conductors are materials that allow current to flow through them, this object is a conductor.

Page No 162:

Question 2:

Nothing happens if you touch a cell but you can get a bad shock if you touch an electrical socket. Justify your answer by giving proper reason.

Answer:

There is not enough voltage in an electric cell to result into a shock. However, electrical sockets are powerful enough to give an electric shock. Hence, nothing happens if we touch a cell, but get a bad shock if we touch an electrical socket.

Page No 162:

Question 3:

Arrangement of electric cell in the electrical circuit affects the amount of current flowing through the circuit. Explain why?

Answer:

The current drawn from an electric cell in a circuit depends on the former's arrangement, as the final terminal voltage of combination depends on the arrangement of the cell.

Page No 162:

Question F:

Match the words with the correct symbols given below:
Closed switch Electric bulb Battery of dry cells Single electric cell Open switch

Figure

Answer:

(a) Battery of dry cells

(b) Single electric cell

(d) Closed switch

(e) Open switch

Page No 164:

Question A.1:

What do you understand by a primary cell?

Answer:

Cells which provide current as a result of an irreversible chemical reaction are called primary cells.

Page No 164:

Question A.2:

What do you mean by a battery?

Answer:

A battery is the collection of one or more cells in which the chemical energy is converted into electrical energy.

Page No 164:

Question A.3:

What is the function of an electric bulb?

Answer:

Function of an electric bulb is to produce light energy from the electricity passing through its filament. The filament gets heated up as the electricity passes through it.

Page No 164:

Question A.4:

Name the material that allows electric current to flow through it easily.

Answer:

Metals are good conductors of electricity; hence, they allow electric current to flow through them easily.
Example: Silver, aluminium, gold, copper, etc.

Page No 164:

Question A.5:

What is the common name of an electric switch?

Answer:

Electric switch is commonly known as the key of an electric circuit. When the key is closed, current flows through the circuit, and when the key is opened, current stops flowing through the circuit.

Page No 164:

Question A.6:

How many terminals does a cell have?

Answer:

A cell has two terminals, i.e. a positive terminal and a negative terminal.

Page No 164:

Question A.7:

Name the circuit component that is used to start or stop the flow of current in the circuit.

Answer:

Key or an electric switch is the component that is used to start or stop the flow of current through the circuit.

Page No 164:

Question A.8:

Will the electric current flow in a circuit in which there is a gap between two wires?

Answer:

No, electric current will not flow through a circuit that has a gap between its two wires, as the circuit is incomplete.

Page No 164:

Question B.1:

Distinguish between open and closed circuits.

Answer:

Open Circuit	Closed Circuit
In an open circuit, the key or switch is open.	In a closed circuit, the key or switch is closed.
Electrical current does not flow through an open circuit.	Electrical current flows through a closed circuit as it is complete.

Page No 164:

Question B.2:

What is the difference between a cell and a battery?

Answer:

Cell	Battery
Cell is a single unit.	Battery is the combination of many cells.

Page No 164:

Question B.3:

Why should an electrician use rubber gloves while repairing an electric switch at your home?

Answer:

Rubber is a bad conductor of electricity or simply an insulator which does not allow the flow of electricity through it. Thus, an electrician uses rubber gloves, while repairing an electrical switch, to protect himself from an electric shock.

Page No 164:

Question B.4:

What is the source of electric current in a cell?

Answer:

In a cell, chemical reaction takes place to produce electricity. Therefore, source of electricity in a cell is the chemical reaction taking place among the chemicals present inside it.

Page No 164:

Question B.5:

What is the importance of electric switch?

Answer:

An electric switch controls the flow of current through a circuit. When the switch is closed, current starts flowing through the circuit, and when it is opened, current stops flowing.

Page No 164:

Question B.6:

How are rechargeable cells different from ordinary primary cells?

Answer:

Ordinary Cells	Rechargeable Cells
Ordinary cells can be used only once.	Rechargeable cells can be charged and reused again and again.
For example, the cells used in torch lights and wall clocks are ordinary cells.	For example, the cells used in cameras and mobiles are rechargeable cells.

Page No 164:

Question B.7:

Why electricity cannot flow in an open circuit?

Answer:

Electricity can not flow in an open circuit because the latter is incomplete. For electricity to flow in an electrical circuit, it should be complete.

Page No 164:

Question C.1:

Distinguish between primary and secondary cells.

Answer:

Primary Cell	Secondary Cell
Primary cells are designed to be used once only, i.e. these cells can be used as long as their chemical mixtures hold power, and after that they becomes useless.	Secondary cells undergo reversible reactions, and they can be recharged once their power diminishes.
For example, dry cells of torch lights and wall clocks	For example, car batteries

Page No 164:

Question C.2:

Give the construction and working of an electric bulb.

Answer:

Construction of an electric bulb is as follows:

An electric bulb comprises a filament, inert gas, two terminals and a glass chamber to protect the inert gas from leaking.

The purpose of an electric bulb is to convert electrical energy to light energy, although some energy is lost as heat. The concept behind the working of a light bulb is - current flowing through a material heats it up and make it glow to produce light.
The current flowing through the filament of the bulb heats the latter and makes it to emit light within the visible range.

Page No 164:

Question C.3:

What do you mean by an electric circuit? Draw the circuit diagram for a circuit having three cells, one bulb and a switch.

Answer:

An electric circuit is a closed path through which the current flows. An electric circuit comprises a switch, a bulb, a cell, etc.When the switch is closed, the circuit is complete and current starts flowing through it. On the other hand, when the switch is open, the circuit is open or incomplete; hence, current stops flowing through it.

Page No 164:

Question C.4:

Distinguish between conductors and insulators. Give three examples of each.

Answer:

S.No.	Conductors	Insulators
1.	Materials which allow current to pass through them are known as conductors.	Materials which don't allow current to pass through them are known as insulators.
2.	Conductors consist of free electrons as charge carriers.	Insulators do not posses free charge carriers.
3.	Examples of conductors: copper, silver and mercury (liquid conductor)	Examples of insulators: plastic, wood and oil (liquid insulator)

Page No 164:

Question C.5:

An electric bulb does not glow sometimes, although it does not fuse. Explain.

Answer:

An electric bulb glows when the circuit is complete and current flows through it. When a bulb fails to glow even if it is not fused, it means that the electric current is not flowing through the circuit.

Page No 164:

Question C.6:

Instead of plastic, can the electric wire used at home be covered with aluminium foil? Give a reason in support of your answer.

Answer:

No, the electric wire used at home should never be covered with aluminium foil as the latter is a good conductor of electricity. If wires are covered with aluminium foils, they will allow the current to flow through them, thereby leading to electrical shock.

Page No 165:

Question C.7:

In the given figure, it is found that the bulb does not glow. Give a reason to support the statement.
Figure

Answer:

Wood is an insulator, i.e. bad conductor of electricity. In the given figure, the electrical circuit is not complete as wood acts as an open switch; hence, the bulb fails to glow.

Page No 165:

Question C.8:

You are advised to wear rubber slippers or shows when handling electrical appliances. Why?

Answer:

Our body is a good conductor of electricity; hence, we are advised to wear rubber slippers when handling an electrical appliance so as to protect ourselves from electrical shocks. Rubber, being an insulator or bad conductor of electricity, acts as an open switch that does not allow the electrical current to flow through our body.

Page No 165:

Question C.9:

Why are electric wires made our of copper of aluminium and not silver even though it is a better conductor of electricity.

Answer:

Even if silver is a better conductor of electricity as compared to copper or aluminium, it is not used in electrical wires because of its huge cost. Copper and aluminium are cheaper than silver; hence, they are used in electric wires.

View NCERT Solutions for all chapters of Class 6

What can act as an electronic switch that opens or closes the circuits for electrical charges?

Chapter 14 Components of the System Unit.

What can act as an electronic switch?

The most common use for a transistor is as a switch, When current flows from base to emitter, the resistance between collector and emitter drops while there is current flow. In a simple on/off switch for an LED, where our signal comes from a signal chip, it would work like in the animation.

Can a diode act as a switch?

Yes, diodes can act as a switch.

How does pn junction diode act as a switch?

The PN junction, when forward biased acts as close circuited and when reverse biased acts as open circuited. Hence the change of forward and reverse biased states makes the diode work as a switch, the forward being ON and the reverse being OFF state.