Electricity – Complete Chapter Notes
Get complete Class 10 Science Electricity Notes for CBSE and NCERT preparation. Revise electric current, potential difference, resistance, Ohm's Law, resistivity, V-I characteristic graphs, formulas, important concepts and numerical problems in one place.
Class 10 Electricity Notes – Complete Chapter Revision
Welcome to these comprehensive Class 10 Electricity Notes designed especially for CBSE Class 10 Science and NCERT Class 10 Science students. Electricity is an important chapter in Class 10 Physics and is regularly tested through concepts, formulas, numerical problems, graphs and application-based questions in school examinations, pre-board exams and board exams.
These Class 10 Science Electricity notes cover electric current, electric charge, potential difference, electric circuits, resistance, Ohm's Law, V-I characteristics, factors affecting resistance, resistivity and important applications of electrical resistance.
Students can use this page for quick revision before exams and for understanding the important formulas and concepts from the Electricity chapter of NCERT Class 10 Science.
Important Electricity Formulas
1. Electric Charge and Electric Current
Electric current is the rate of flow of electric charge through a conductor.
Where I = current, Q = electric charge and t = time.
- SI unit of charge: Coulomb (C)
- SI unit of current: Ampere (A)
- 1 ampere means that 1 coulomb of charge flows through a conductor in 1 second.
2. Electric Potential and Potential Difference
Potential difference between two points is the work done in moving a unit charge from one point to another.
V = potential difference, W = work done, Q = charge
- SI unit: Volt (V)
- Potential difference is measured using a voltmeter.
- A voltmeter is connected in parallel across the component.
3. Electric Circuit
An electric circuit is a closed conducting path through which electric current can flow.
- Electric cell or battery
- Connecting wires
- Electric switch or key
- Resistor or other electrical appliance
- Ammeter
- Voltmeter
4. Ammeter and Voltmeter
| Instrument | Measures | Connection |
|---|---|---|
| Ammeter | Electric current | Connected in series |
| Voltmeter | Potential difference | Connected in parallel |
5. Electric Resistance
Resistance is the property of a conductor that opposes the flow of electric current through it.
- SI unit: Ohm (Ω)
- Resistance is represented by the symbol R.
- A conductor has a resistance of 1 Ω if a potential difference of 1 V produces a current of 1 A through it.
6. Ohm's Law
Ohm's Law states that the potential difference across the ends of a conductor is directly proportional to the current flowing through it, provided the temperature and other physical conditions remain constant.
Therefore,
Here, R is the constant of proportionality and represents the resistance of the conductor.
7. Ohm's Law Experiment
The experimental verification of Ohm's Law involves connecting a battery, key, resistor, ammeter and voltmeter in an electric circuit.
- Connect the resistor in series with the battery, key and ammeter.
- Connect the voltmeter in parallel across the resistor.
- Close the key and note the ammeter and voltmeter readings.
- Change the number of cells to change the potential difference.
- Record different values of V and I.
- Calculate V/I for each observation.
Observation Table
| Potential Difference V (V) | Current I (A) | V/I (Ω) |
|---|---|---|
| 1 | 0.2 | 5 |
| 2 | 0.4 | 5 |
| 3 | 0.6 | 5 |
8. V-I Characteristic Graph
For an ohmic conductor, the graph between potential difference V and current I is a straight line passing through the origin.
- V is directly proportional to I.
- The graph is a straight line through the origin.
- The slope of a V-I graph gives resistance.
9. Factors Affecting Resistance
The resistance of a conductor depends on several factors.
| Factor | Effect on Resistance |
|---|---|
| Length of conductor | Resistance increases with length. |
| Area of cross-section | Resistance decreases when area increases. |
| Nature of material | Different materials have different resistivities. |
| Temperature | Resistance generally changes with temperature. |
For a uniform conductor:
10. Resistivity
Resistivity is a property of a material that indicates how strongly it resists the flow of electric current.
Therefore,
- ρ = resistivity
- R = resistance
- L = length of conductor
- A = area of cross-section
11. Resistance vs Resistivity
| Resistance | Resistivity |
|---|---|
| Depends on length and cross-sectional area. | Depends mainly on the nature of the material and temperature. |
| Symbol: R | Symbol: ρ |
| SI unit: Ω | SI unit: Ω m |
| R = V/I | ρ = RA/L |
12. Conductors, Insulators, Semiconductors & Heating Elements
| Type | Examples | Important Property |
|---|---|---|
| Conductors | Copper, Aluminium | Low resistance and low resistivity |
| Insulators | Rubber, Plastic | Very high resistance |
| Semiconductors | Silicon, Germanium | Electrical conductivity between conductors and insulators |
| Heating Elements | Nichrome | High resistivity and high melting point |
13. Important Electricity Numericals
Using R = V/I:
R = 12/2 = 6 Ω
Using V = IR:
V = 3 × 4 = 12 V
Using I = Q/t:
I = 60/20 = 3 A
I = V/R
I = 20/10 = 2 A
14. Important Board-Style Questions
15. Application-Based Question
At 20°C, the resistivities of three materials A, B and C are:
A = 1.6 × 10-8 Ωm
B = 6.84 × 10-8 Ωm
C = 1012 Ωm
Identify which material is likely to be a metal, which could be an alloy and which could be an insulator.
16. Quick Concept Check
17. One-Page Quick Revision
| Concept | Key Point |
|---|---|
| Electric Current | I = Q/t |
| Potential Difference | V = W/Q |
| Resistance | R = V/I |
| Ohm's Law | V = IR |
| V-I Graph | Slope gives resistance |
| Resistance and Length | R ∝ L |
| Resistance and Area | R ∝ 1/A |
| Resistivity | ρ = RA/L |
| Resistance Formula | R = ρL/A |
| Resistance Unit | Ohm (Ω) |
| Resistivity Unit | Ohm metre (Ωm) |
| Ammeter | Connected in series |
| Voltmeter | Connected in parallel |
18. Exam Tips for Class 10 Electricity
- Learn all important formulas before attempting numericals.
- Always write the given quantities and required quantity.
- Write the formula before substituting values.
- Do not forget SI units in numerical answers.
- Remember the difference between resistance and resistivity.
- Remember that an ammeter is connected in series.
- Remember that a voltmeter is connected in parallel.
- Practice V-I graph questions.
- Revise questions based on factors affecting resistance.
- Practice application-based and competency-based questions.
📚 Prepare Better for Your Class 10 Science Exam
Finished revising the Electricity notes? Now practice important exam-oriented questions from the same chapter.