CBSE Class 10 Science Electricity: Notes, Formulae and Quick Revision

Chapter-wise notes, formulae, methods, solved examples and mistake checks. Choose a topic, then revise the section you need.

Continue with question practice

CBQs Important Questions PYQs

ChapterTopic

Quick Concepts Revision replaces question-format filters with study tools for the selected chapter and topic.

Electricity · Electric Current and Circuit

Electric Current and Circuit

Start with charge flow, potential difference and the correct way to read a simple circuit.

Quick notes

Follow the units

Current is measured in ampere (A), potential difference in volt (V), resistance in ohm ( $Ω$ ), power in watt (W), and energy in joule (J).

Read circuit connections carefully

An ammeter is connected in series. A voltmeter is connected in parallel across the component whose potential difference is measured.

Formulae

Current

$I = \frac{Q}{t}$

Charge flowing per second.

Potential difference

$V = \frac{W}{Q}$

Work done per unit charge.

Key methods

Circuit diagrams

Identify the component, then trace the path of current. Check whether a meter is connected in series or parallel before choosing an answer.

Solved example

A charge of $12$ C flows in $3$ s. Find the current.

1.Use $I = Q / t$ .
2.Substitute $I = 12/3$ .

The current is $4$ A.

Common mistakes

Connecting an ammeter in parallel.
Forgetting to write the unit ampere (A) with current.

Practice

Practise Electricity Important Questions Competency Questions Previous Year Questions

Electricity · Ohm's Law and Resistance

Ohm's Law and Resistance

Connect voltage, current and resistance, then use graphs and units confidently in numerical questions.

Quick notes

Understand the I-V graph

For an ohmic conductor, the I-V graph is a straight line through the origin. With I on the vertical axis and V on the horizontal axis, slope is $I / V = 1/ R$ .

Resistance depends on the conductor

A longer wire has more resistance, while a thicker wire has less resistance.

Formulae

Ohm's law

$V = I R$

Use when temperature and physical conditions are constant.

Resistance of a wire

$R = ρ \frac{L}{A}$

Longer wire means more resistance; greater area means less resistance.

Key methods

Numerical questions

Write the given values with units, select one formula, substitute consistently, and write the final unit. Do not mix milliampere with ampere.

Graph questions

Check the axes first. For an I-on-vertical and V-on-horizontal graph, slope equals $I / V$ , so a steeper line has lower resistance.

Solved example

A $12$ V source is connected across a $4Ω$ resistor. Find current and power.

1.Use Ohm's law: $I = V / R = 12/4 = 3$ A.
2.Use $P = V I = 12 \times 3$ .

The current is $3$ A and the power is $36$ W.

Common mistakes

Using $V / I$ as the slope when I is on the vertical axis and V is on the horizontal axis.
Using Ohm's law without checking the units.

Practice

Practise Electricity Important Questions Competency Questions Previous Year Questions

Electricity · Resistance Combination and Electric Power

Resistance Combination and Electric Power

Finish the chapter by comparing series and parallel circuits, then apply the power and heating relationships.

Quick notes

Compare circuit combinations

In series, current is the same through every component. In parallel, potential difference is the same across each branch.

Choose the right power formula

Use the form of the power formula that matches the values given in the question.

Formulae

Series resistance

$R = R_{1} + R_{2} + \dots$

Resistances add directly in series.

Parallel resistance

$\frac{1}{R} = \frac{1}{R _{1}} + \frac{1}{R _{2}} + \dots$

Equivalent resistance is smaller than the smallest branch resistance.

Power and heating

$P = V I = I^{2} R = \frac{V ^{2}}{R}$ and $H = I^{2} R t$

Match the formula to the values provided.

Key methods

Series and parallel circuits

First identify the connection. In series, use the same current; in parallel, use the same potential difference across each branch.

Solved example

Two $6Ω$ resistors are connected in series across $12$ V. Find the circuit current.

1.Add the resistances: $R = 6 + 6 = 12Ω$ .
2.Use $I = V / R = 12/12$ .

The circuit current is $1$ A.

Common mistakes

Using the series-resistance rule for a parallel circuit.
Adding branch currents before identifying whether the circuit is series or parallel.

Practice

Practise Electricity Important Questions Competency Questions Previous Year Questions

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CBSE 10

CBSE Class 10 Science Electricity: Notes, Formulae and Quick Revision

Chapter-wise notes, formulae, methods, solved examples and mistake checks. Choose a topic, then revise the section you need.

Continue with question practice

CBQs Important Questions PYQs

ChapterTopic

Quick Concepts Revision replaces question-format filters with study tools for the selected chapter and topic.

Electricity · Electric Current and Circuit

Electric Current and Circuit

Start with charge flow, potential difference and the correct way to read a simple circuit.

Quick notes

Follow the units

Current is measured in ampere (A), potential difference in volt (V), resistance in ohm ( $Ω$ ), power in watt (W), and energy in joule (J).

Read circuit connections carefully

An ammeter is connected in series. A voltmeter is connected in parallel across the component whose potential difference is measured.

Formulae

Current

$I = \frac{Q}{t}$

Charge flowing per second.

Potential difference

$V = \frac{W}{Q}$

Work done per unit charge.

Key methods

Circuit diagrams

Identify the component, then trace the path of current. Check whether a meter is connected in series or parallel before choosing an answer.

Solved example

A charge of $12$ C flows in $3$ s. Find the current.

1.Use $I = Q / t$ .
2.Substitute $I = 12/3$ .

The current is $4$ A.

Common mistakes

Connecting an ammeter in parallel.
Forgetting to write the unit ampere (A) with current.

Practice

Practise Electricity Important Questions Competency Questions Previous Year Questions

Electricity · Ohm's Law and Resistance

Ohm's Law and Resistance

Connect voltage, current and resistance, then use graphs and units confidently in numerical questions.

Quick notes

Understand the I-V graph

For an ohmic conductor, the I-V graph is a straight line through the origin. With I on the vertical axis and V on the horizontal axis, slope is $I / V = 1/ R$ .

Resistance depends on the conductor

A longer wire has more resistance, while a thicker wire has less resistance.

Formulae

Ohm's law

$V = I R$

Use when temperature and physical conditions are constant.

Resistance of a wire

$R = ρ \frac{L}{A}$

Longer wire means more resistance; greater area means less resistance.

Key methods

Numerical questions

Write the given values with units, select one formula, substitute consistently, and write the final unit. Do not mix milliampere with ampere.

Graph questions

Check the axes first. For an I-on-vertical and V-on-horizontal graph, slope equals $I / V$ , so a steeper line has lower resistance.

Solved example

A $12$ V source is connected across a $4Ω$ resistor. Find current and power.

1.Use Ohm's law: $I = V / R = 12/4 = 3$ A.
2.Use $P = V I = 12 \times 3$ .

The current is $3$ A and the power is $36$ W.

Common mistakes

Using $V / I$ as the slope when I is on the vertical axis and V is on the horizontal axis.
Using Ohm's law without checking the units.

Practice

Practise Electricity Important Questions Competency Questions Previous Year Questions

Electricity · Resistance Combination and Electric Power

Resistance Combination and Electric Power

Finish the chapter by comparing series and parallel circuits, then apply the power and heating relationships.

Quick notes

Compare circuit combinations

In series, current is the same through every component. In parallel, potential difference is the same across each branch.

Choose the right power formula

Use the form of the power formula that matches the values given in the question.

Formulae

Series resistance

$R = R_{1} + R_{2} + \dots$

Resistances add directly in series.

Parallel resistance

$\frac{1}{R} = \frac{1}{R _{1}} + \frac{1}{R _{2}} + \dots$

Equivalent resistance is smaller than the smallest branch resistance.

Power and heating

$P = V I = I^{2} R = \frac{V ^{2}}{R}$ and $H = I^{2} R t$

Match the formula to the values provided.

Key methods

Series and parallel circuits

First identify the connection. In series, use the same current; in parallel, use the same potential difference across each branch.

Solved example

Two $6Ω$ resistors are connected in series across $12$ V. Find the circuit current.

1.Add the resistances: $R = 6 + 6 = 12Ω$ .
2.Use $I = V / R = 12/12$ .

The circuit current is $1$ A.

Common mistakes

Using the series-resistance rule for a parallel circuit.
Adding branch currents before identifying whether the circuit is series or parallel.

Practice

Practise Electricity Important Questions Competency Questions Previous Year Questions