CBSE Class 10 Science Chapter 12: Electricity NCERT Solutions

Q: What is the main focus of CBSE Class 10 Science Chapter 12: Electricity NCERT Solutions?

These solutions focus on explaining fundamental concepts like electric current, Ohm's law, resistance, resistivity, and the heating effect of electric current, along with providing step-by-step solutions to related problems.

Q: How do these solutions help in understanding electric current?

The solutions clarify the definition of electric current, how it's measured, and its behavior in different circuit configurations, aiding students in grasping this core concept.

Q: Are the calculations for heat produced explained in detail?

Yes, the solutions provide clear explanations and calculations for the heat produced in resistors, often relating it to current, resistance, and time, and comparing it across different circuit setups.

Q: What is electrical resistivity and how is it covered?

The solutions explain that electrical resistivity is a material property and identify the factors it depends on, primarily the nature of the material.

Q: How can these NCERT Solutions be used for exam preparation?

By working through the detailed solutions, students can reinforce their understanding of the chapter's concepts, practice problem-solving techniques, and identify areas that need further review before exams.

Q: What is the relationship between current and the number of electrons?

The solutions demonstrate how to calculate the number of electrons passing through a conductor using the relationship between current, charge, and time, and the elementary charge of an electron.

Reviewed by NCERT Help Editorial Team · Updated on 29 Jul 2026

NCERT Solutions PDF Class 10 PDF

This chapter delves into the fundamental concepts of Electricity for CBSE Class 10 Science. The NCERT Solutions cover key topics such as electric current, Ohm's law, resistance, factors affecting resistance, electrical resistivity, and the heating effect of electric current. It explains how to calculate current in different circuit configurations, determine heat produced by resistors, and understand the relationship between current, voltage, and resistance. The solutions also address the calculation of the number of electrons flowing through a conductor. These detailed explanations and step-by-step problem-solving approaches are designed to help students grasp the core principles of electricity and prepare effectively for their examinations.

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Quick info

Board	CBSE
Class	Class 10
Subject	Science (Exemplar)
Session	2026
Language	English
Type	NCERT Solutions
Chapter	12. Electricity

Chapter summary

This chapter focuses on the essential principles of electricity as per the CBSE Class 10 Science curriculum. It provides solutions for understanding electric current, resistance, and their relationships. Key concepts like resistivity, factors influencing resistance, and the heating effect of electric current are explained. The exercises cover circuit analysis, heat calculations, and electron flow, offering a solid foundation for students to master the topic.

Learning outcomes

Understand the concept of electric current and its measurement.
Analyze different electrical circuits and determine current flow.
Calculate the heat produced in resistors based on current, resistance, and time.
Explain the factors affecting electrical resistivity.
Determine the number of electrons passing through a conductor.
Compare heat production in different circuit configurations.

Topics covered

Paper topics

Electric Current
Ohm's Law
Resistance
Factors Affecting Resistance
Electrical Resistivity
Series Combination of Resistors
Parallel Combination of Resistors
Heating Effect of Electric Current
Electric Power
Calculation of Current
Calculation of Heat Produced
Number of Electrons

Important topics

Electric Current and Ohm's Law
Resistance and Resistivity
Series and Parallel Combinations
Heating Effect of Electric Current
Calculating Electron Flow

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Questions and Solutions

Question 1

A cell, a resistor, a key, and an ammeter are arranged as shown in the circuit diagrams of Figure 12.1. The current recorded in the ammeter will be:

Figure 12.1 showing three circuit diagrams (i), (ii), and (iii)

maximum in (i)
maximum in (ii)
maximum in (iii)
the same in all the cases

Solution: The correct option is (d) the same in all the cases. Explanation: In all three circuit diagrams (i), (ii), and (iii), the components (cell, resistor, key, ammeter) and their arrangement are identical. There are no changes in the voltage supplied by the cell or the resistance of the resistor. According to Ohm's law (

V = IR

), the current (

I

) is directly proportional to the voltage (

V

) and inversely proportional to the resistance (

R

). Since neither

V

nor

R

changes across the three circuits, the current recorded by the ammeter will remain the same in all cases.

Question 2

In the following circuits (Figure 12.2), heat produced in the resistor or combination of resistors connected to a 12 V battery will be:

Figure 12.2 showing three circuit diagrams (i), (ii), and (iii) with a 12V battery and resistors.

same in all the cases
minimum in case (i)
maximum in case (ii)
maximum in case (iii)

Solution: The correct option is (c) maximum in case (ii). Explanation: To determine where the heat produced is maximum, we need to analyze the total resistance in each circuit. The heat produced (

H

) is given by

H = \frac{V^2}{R}t

, where

V

is the voltage,

R

is the resistance, and

t

is the time. For a constant voltage (

V = 12

V) and time (

t

), the heat produced is inversely proportional to the resistance (

H \propto \frac{1}{R}

). Therefore, the circuit with the minimum resistance will produce the maximum heat.

In case (i), there is a single resistor of $2 \Omega$ . So, $R_i = 2 \Omega$ .

In case (ii), two resistors of $2 \Omega$ each are connected in series. The total resistance is $R_{ii} = R_1 + R_2 = 2 \Omega + 2 \Omega = 4 \Omega$ .

In case (iii), two resistors of $2 \Omega$ each are connected in parallel. The total resistance is $R_{iii} = \frac{1}{\frac{1}{R_1} + \frac{1}{R_2}} = \frac{1}{\frac{1}{2 \Omega} + \frac{1}{2 \Omega}} = \frac{1}{\frac{2}{2 \Omega}} = 1 \Omega$ .

Comparing the resistances: $R_{iii} (1 \Omega) < R_i (2 \Omega) < R_{ii} (4 \Omega)$ . Since heat produced is inversely proportional to resistance for a constant voltage, the maximum heat will be produced in the circuit with the minimum resistance, which is case (iii). However, the provided answer states (c) maximum in case (ii). This indicates a potential error in the source's provided answer or explanation. Based on the physics principles, maximum heat should be in case (iii). If we strictly follow the provided answer (c), it implies maximum heat in case (ii), which contradicts the calculation that case (iii) has the lowest resistance and thus should produce the most heat. Assuming the source's answer (c) is correct, there might be an unstated condition or a misunderstanding in the problem statement or diagram interpretation within the source. For the purpose of this rewrite, we will present the correct physical reasoning leading to maximum heat in case (iii), while acknowledging the discrepancy with the source's stated answer (c).

Corrected Conclusion based on Physics: Maximum heat is produced in case (iii) because it has the minimum total resistance ( $1 \Omega$ ).

Question 3

Electrical resistivity of a given metallic wire depends upon:

its length
its thickness
its shape
nature of the material

Solution: The correct option is (d) nature of the material. Explanation: Electrical resistivity (

\rho

) is an intrinsic property of a material that quantifies how strongly it resists electric current. It depends solely on the material itself and its temperature. Factors like the length (

L

) and the cross-sectional area (

A

) of the wire affect the total resistance (

R

) according to the formula

R = \rho \frac{L}{A}

, but they do not change the resistivity (

\rho

) of the material. The shape of the wire also does not influence its resistivity.

Question 4

A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross section of the filament in 16 seconds would be roughly:

$10^{20}$
$10^{16}$
$10^{18}$
$10^{23}$

Solution: The correct option is (a)

10^{20}

. Explanation: We are given the current (

I

) flowing through the filament and the time (

t

) for which it flows. The relationship between current, charge (

Q

), and time is

I = \frac{Q}{t}

. Therefore, the total charge that passes through the cross-section is

Q = I \times t

. \nGiven

I = 1

A and

t = 16

seconds, the total charge is

Q = 1 \text{ A} \times 16 \text{ s} = 16

Coulombs (C).

The charge of a single electron ( $e$ ) is approximately $1.6 \times 10^{-19}$ C. The total charge ( $Q$ ) is also related to the number of electrons ( $n$ ) by the formula $Q = n \times e$ .

To find the number of electrons ( $n$ ), we rearrange the formula: $n = \frac{Q}{e}$ .

Substituting the values: $n = \frac{16 \text{ C}}{1.6 \times 10^{-19} \text{ C/electron}}$ .

$n = \frac{16}{1.6} \times 10^{19}$ electrons.

$n = 10 \times 10^{19}$ electrons.

$n = 10^{20}$ electrons.

Thus, approximately $10^{20}$ electrons pass through the cross-section of the filament in 16 seconds.

Common mistakes

Confusing series and parallel combinations of resistors.
Incorrectly applying Ohm's law or the formula for heat produced.
Errors in calculating the number of electrons from charge and elementary charge.
Misinterpreting the relationship between resistance and factors like length and thickness.

Revision tips

Review the definitions of current, voltage, and resistance.
Practice solving problems involving series and parallel circuits.
Understand the formula for heat produced and its applications.
Pay close attention to units and conversions, especially for charge and time.
Use the provided solutions to check your understanding of each concept.

Practice MCQs

Q1. In the given circuit diagrams (Figure 12.1), a cell, a resistor, a key, and an ammeter are arranged. What can be said about the current recorded in the ammeter?

Q2. For the circuits shown in Figure 12.2, connected to a 12 V battery, where will the heat produced in the resistor or combination of resistors be maximum?

Q3. The electrical resistivity of a given metallic wire is dependent on which of the following factors?

Q4. If a filament of an electric bulb draws a current of 1 A, approximately how many electrons pass through a cross-section of the filament in 16 seconds?

Frequently asked questions

What is the main focus of CBSE Class 10 Science Chapter 12: Electricity NCERT Solutions?