# Basic Components of Electricity Class-8th Goyal Brothers ICSE Physics Solution Chapter-8 Unit-3

Basic Components of Electricity Class-8th Goyal Brothers Physics Solutions Chapter-8 (Electricity), unit-3 (Basic Components of Electricity). We Provide Step by Step Answers of Objective, True False, Incorrect and Correct, Fill in the blanks, Match the following , Short/Long Answer Type of Chapter-8 (Electricity), unit-3 (Basic Components of Electricity) Visit official Website  CISCE  for detail information about ICSE Board Class-8.

## Basic Components of Electricity Class-8th Goyal Brothers ICSE Physics Solution Chapter-8 Unit-3

 Board ICSE Class 8th Subject Physics Book Name Goyal Brothers Chapter-8 Electricity Unit-3 Basic Components of Electricity Topic Solution of exercise questions Session 2023-24

### OBJECTIVE QUESTION

Basic Components of Electricity Class-8th Goyal Brothers ICSE Physics Solution Chapter-8 Unit-3

#### Que: A. Fill in the blank spaces by choosing the correct words from the list given below:

List: fuse, insulation, source, sink, sum

1. Battery is a small __source__ of electricity.

2. In the series connection of cells, overall emf of the battery is algebraic __sum__ of all individual cells connected in series.

3. Electric __fuse__ helps in disconnecting a faulty electric circuit and thus, prevents an electric fire.

4. The earth can be regarded as an electric __sink___ .

5. In order to distinguish, which wire is live or neutral or of earth, the __insulation__ is given a specific colour.

#### Que: B. Statements given below are incorrect. Write the correct statements:

##### Question: 1. In series connection of cells, positive terminals of all cells are connected to one point and negative terminals of all cells to other point.

Answer: In series connection of cells, negative terminals of all cells are connected to one point and positive terminals of all cells to other point.

##### Question: 2. Electric fuse does not need replacement, whenever circuit gets overloaded, the components of fuse sense it and put the circuit in off position.

Answer: While using fuse whenever overloading occurs the fuse wire melts and it has to be replaced to complete the circuit. These days maniature circuits breakers (MCBs) are switches that turn off automatically when there is an overload or a short circuit.

##### Question: 3. After getting a large amount of electrons, the potential of the earth increases enormously.

Answer: After getting a large amount of electrons, the potential of the earth decreases enormously.

##### Question: 4. Inside the house earth wire is connected to the input terminal of kWh meter.

Answer: Inside the house earth wire is connected to input terminal of kWh meter​

##### Question: 5. In case of double insulated hair dryer there is great need of earth wire because the case of it is made of a conducting material.

Answer: Double insulation protects the user of the appliance from an electrical shock by preventing any possibility of the enteral casing becoming live ( the live wire can not touch the casing even if wires inside become loose), thus eliminating the need for an earth connection.

#### Que: C. Write ‘True’ or ‘False’ for the following statements:

 Statements True/False 1. Cells can be connected in series, in parallel and as well as combination of both the series and parallel. T 2. Electric fuse is the strongest point in an electric circuit, which melts but does not break the circuit in case of faulty electric circuit. F 3. The earth does not offer any resistance, when current flows into it. F 4. Conventional current flows from the negative terminal of the power source to the positive terminal. T 5. The consumer pays the cost of electrical energy consumed in unit of kilowatt hour (kWh). T

#### Que: D. Tick (√) the most appropriate answer:

1. Battery is a collection of cells connected in

(a) series

(b) parallel

(c) both (a) and (b)

(d) all of these

Answer: option (a) series is correct.

2. In case of fluctuations of current or overloading, the weakest point in circuit which melts and breaks the circuit, is

(a) circuit breaker

(b) electric fuse

(c) earthing

(d) all of these

Answer: option (b) electric fuse is correct.

3. When an earthed electric appliance gets short circuited, then the current from its metal body flows into the

(a) electric fuse

(b) live wire

(c) neutral wire

(d) earth

Answer: option (c) neutral wire is correct.

4. According to the new international convention, the colour of insulation for live wire is

(a) red

(b) brown

(c) green

(d) blue

Answer: option (b) brown is correct.

5. Which of the following wires does connect the metal case of the device to the earth?

(a) live wire

(b) neutral wire

(c) earth wire

(d) any of these

Answer: option (c) earth wire is correct.

#### Que: E. Match the statements in Column A, with those in Column B:

 Column A Column B 1. A small source of electricity. (a) Body of the kWh meter 2. A safety device, which melts and breaks the circuit in an abnormal situation. (b) Miniature circuit breaker 3. A safety device, which sense overloading of the circuit and put the circuit in off position. (c) Battery 4. A safety device, which is protected the user from receiving an electric shock by touching the metal body of short circuited device. (d) Electric fuse 5. The terminal from which earth wire is connected inside the house. (e) Earthing

 Column A Column B 1. A small source of electricity. (a) Battery 2. A safety device, which melts and breaks the circuit in an abnormal situation. (b) Electric fuse 3. A safety device, which sense overloading of the circuit and put the circuit in off position. (c) Miniature circuit breaker 4. A safety device, which is protected the user from receiving an electric shock by touching the metal body of short circuited device. (d) Earthing 5. The terminal from which earth wire is connected inside the house. (e) Body of the kWh meter

### STUDY QUESTIONS

Basic Components of Electricity Class-8th Goyal Brothers ICSE Physics Solution Chapter-8 Unit-3

#### Question: 1. (a) Define battery. How are overall emf of battery related to emf of the cells when connected is series?

Answer: A battery is a device that converts chemical energy contained within its active materials directly into electric energy by means of an electrochemical oxidation-reduction (redox) reaction. The overall emf of the battery is the algebraic sum of all individual cells connected in series.

#### (b) How are internal resistance of individual cells related to internal resistance of the battery in case of series connection?

Answer: The internal resistance of the battery will be equal to the sum of the internal resistance of the individual cells.

#### Question: 2. Define electric fuse. How is it acted as a safety device in an electric circuit?

Answer: An electrical fuse is a low melting point copper or other metal wire that breaks due to heat caused by overvoltage or high load to avoid short circuit or failure to the device. A fuse is an electrical safety device that has the capability to protect an electric circuit from excessive electric current.

#### Question: 3. What do you mean by miniature circuit breaker? How is it used in an electric circuit to protect an electric appliance?

Answer: Miniature Circuit Breaker is a safety accessory with an electro-mechanical mechanism of action. The fuse breaks the circuit if a fault in an appliance causes too much current flow.

#### Question: 4. Define earthing. How does earthing an appliance help?

Answer: Earthing is defined as “the process in which the instantaneous discharge of the electrical energy takes place by transferring charges directly to the earth through low resistance wire.” Earthing is used to protect you from an electric shock.

#### Question: 5. Describe identification and function of live wire, neutral wire and earth wire in an electric circuit.

Answer: The live wire carries current from the source to the device (load), while the neutral wire is for the return path of the current from device (load) to the source. The earth wire passes the current to the earth.

#### Question: 6. (a) How is household energy consumption calculated in kilowatt hour (kWh)?

Answer: The household electrical energy or the electricity bill is calculated on the basis of the number of kilowatt-hours (kWh) used. One kilowatt-hour is also simply called ‘one unit’.

#### (b) Explain the dangers of electricity and the safety precautions required.

Answer: The main hazards of working with electricity are: electric shock and burns from contact with live parts. keep electrical equipment dry and away from water prevents damage to appliances and can protect against personal injury and electrocution.

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