These Notes for Class 10 Science Chapter 11 Electricity give you a fast, concept-first revision of the whole chapter, built on the latest 2026-27 CBSE syllabus. They cover electric current and circuits, potential difference, Ohm's law, resistance and resistivity, resistors in series and parallel, the heating effect of current (Joule's law), and electric power and energy measured in kilowatt-hours.
- Every formula explained with its meaning, the correct units, and a fully worked solved example so you can attempt board numericals with confidence.
- Full coverage of electric current, Ohm's law, resistance, resistivity, series and parallel resistors, Joule's law of heating and electric power with labelled circuit diagrams.
- Notes aligned with the 2026-27 CBSE Class 10 Science syllabus and written for the board exam; no NEET or JEE references because this is a Class 10 board chapter.
These Collegedunia revision notes are curated by Science subject experts, mapped to the 2026-27 NCERT textbook, and refined against the last five years of CBSE Class 10 Science board papers.
Student Feedback: What 13,500 students told us about this chapter
81% of Class 10 students said the parallel resistance formula was where they lost the most marks, adding resistances directly instead of using the reciprocal sum. 3 out of 5 students told us that learning series and parallel side by side, and writing the formula before substituting, fixed most of their numerical slips before the board exam.
Toppers found that memorising the three forms of power, "P = VI = I squared R = V squared by R," and picking the form that matches the data given, saved 10 to 15 minutes in the exam, and the average student spent 3 to 4 hours on these notes across the first read and the final revision.
Source: 2026-27 Class 10 Science student poll. Sample of 13,500 students from CBSE schools across 14 states, conducted before the 2026 boards.
What the Notes for Class 10 Science Chapter 11 Electricity Cover
This chapter studies what an electric current is, what pushes charge around a circuit (potential difference), and the rule tying current and voltage in a metal wire (Ohm's law). These notes compress the NCERT chapter into exam-ready blocks:
- Current and voltage: rate of flow of charge, the circuit, potential difference, ammeter and voltmeter.
- Ohm's law and resistance: V = IR, the V-I graph, resistance, resistivity and its factors.
- Combinations: resistors in series and parallel.
- Heating, power and energy: Joule's law, the fuse, the three forms of power, the kilowatt-hour.
Source: Magnet Brains on YouTube
Electric Current and Electric Circuit in Class 10 Science
The flow of electric charge through a conductor is an electric current. It needs a continuous, closed path, the electric circuit; break it and the current stops. Current is the rate of flow of charge crossing any cross-section each second:
- Charge (Q): coulomb (C); charge on one electron is 1.6 × 10−19 C.
- Current (I): ampere (A); 1 A = 1 C/s.
Current is measured by an ammeter, always connected in series. The moving charges are electrons (negative), but by convention current flows from the positive to the negative terminal in the outer circuit, the opposite of the way electrons drift.
Electric Potential and Potential Difference in Class 10 Science
Charge does not flow on its own, just as water in a flat pipe stays still without a pressure difference. For charge, the equivalent is the potential difference, set up by a cell: the work done to move a unit charge between two points.
- The SI unit is the volt (V); 1 V = 1 J/C (1 J of work moving 1 C of charge).
- Potential difference is measured by a voltmeter, always connected in parallel across the two points.
Quick numerical: moving 2 C across 12 V needs W = V × Q = 12 × 2 = 24 J.
Ohm's Law and the V-I Graph in Class 10 Science
Ohm's law says that at constant temperature the potential difference V across a conductor is directly proportional to the current I through it.
Rearranged: R = V / I and I = V / R
R is the resistance, in ohm (Ω); 1 Ω = 1 V/A. At fixed voltage, doubling R halves the current.
- The V-I graph: for a metal wire at constant temperature, V against I is a straight line through the origin, and its slope equals R.
- Ohm's law holds only for ohmic conductors; a glowing bulb filament gives a curve, not a straight line.
Solved example: a 100 Ω heater coil on 220 V draws I = V/R = 220/100 = 2.2 A.
Resistance, Resistivity and the Factors That Affect It in Class 10 Science
Resistance opposes the flow of charge. For a uniform wire it depends on length, cross-section area, and material:
- Length: R ∝ l, so a longer wire has more resistance.
- Area: R ∝ 1/A, so a thicker wire has less resistance.
- Material: ρ is fixed for the material; for metals both R and ρ rise with temperature.
Resistivity tells us how strongly a material opposes current, regardless of shape. Metals have low resistivity; insulators like glass have huge resistivity. Common values:
| Material | Resistivity (Ω m) |
|---|---|
| Copper (wiring) | 1.62 × 10−8 |
| Aluminium (power lines) | 2.63 × 10−8 |
| Tungsten (bulb filament) | 5.20 × 10−8 |
| Nichrome (heater coil) | 100 × 10−6 |
| Glass (insulator) | 1010 to 1014 |
Nichrome (high resistivity, does not burn easily) is used in heaters; tungsten, with its high melting point, is used for bulb filaments.
Resistors in Series and Parallel in Class 10 Science
Resistors are joined end to end (series) or across the same two points (parallel). Telling them apart is a high-frequency skill.
In series the same current flows through each resistor and the voltage is shared. In parallel each resistor has the same voltage and the current splits among the branches.
Parallel: 1/Rp = 1/R1 + 1/R2 + 1/R3 (smaller than the smallest)
Home appliances are wired in parallel: each gets the full 220 V, and switching one off does not break the others. In series, one dead bulb kills the whole line.
Heating Effect of Electric Current and Joule's Law in Class 10 Science
In a purely resistive circuit, the cell's energy all turns into heat. This heating effect makes heaters, irons, toasters and bulb filaments work.
Heat is proportional to the square of the current, the resistance, and the time.
A fuse is a thin wire of low melting point, placed in series. If the current rises above a safe value, the fuse heats up, melts, and breaks the circuit before the wiring is damaged. An iron or heater uses a high-resistance nichrome coil that gets red-hot, while the thick copper cord stays cool.
Solved example: if 100 J of heat is produced each second in a 4 Ω resistor, then I = √(100/4) = 5 A and V = IR = 20 V.
Electric Power and Energy in Kilowatt-hours in Class 10 Science
Power is the rate at which energy is used, the number printed on every appliance ("60 W"). The three forms below are equal; choose the one that matches the data.
The SI unit is the watt (W); 1 kilowatt = 1000 W. The joule is too small for bills, so electricity is sold in kilowatt-hours (kW h), called "units": the energy used when 1 kW runs for 1 hour.
1 kW h = 1000 W × 3600 s = 3.6 × 106 J
Solved example: a 400 W fridge running 8 hours a day for 30 days uses E = 400 × 8 × 30 = 96 kW h; at Rs 3.00 per unit the cost is Rs 288.00.
Quick Revision Strip and Common Exam Traps for Electricity
Key formulae for last-minute revision: I = Q/t; V = W/Q; V = IR; R = ρl/A; Rs = R1 + R2 + R3; 1/Rp = 1/R1 + 1/R2 + 1/R3; H = I²Rt = VIt; P = VI = I²R = V²/R; 1 kW h = 3.6 × 106 J.
Repeat-offender mistakes: adding parallel resistances directly instead of reciprocals; forgetting to convert minutes/hours to seconds; confusing the watt (power) with the kilowatt-hour (energy); swapping the ammeter (series) and voltmeter (parallel); and applying V = IR to a glowing filament.
Previous Year Question Trends from the Electricity Chapter
This chapter is tested mainly through circuit numericals, Ohm's law and the V-I graph, series and parallel combinations, Joule's law and appliance running cost in kilowatt-hours, carrying 2 to 5 marks each.
Also Check: The full set of CBSE board paper questions for this chapter, with step-by-step answers, is in the downloadable PDF above.
Other Resources for Class 10 Science Chapter 11 Electricity
Pair these revision notes with the matching NCERT Solutions, the formula sheet, handwritten notes and the official NCERT book chapter. All resources for Class 10 Science Chapter 11 Electricity are linked below.
| Resource | What it covers | Open |
|---|---|---|
| Notes | Concept-first revision notes on electric current, Ohm's law, resistance and resistivity, series and parallel resistors, Joule's law and electric power. | You are here |
| NCERT Solutions | Step-by-step answers to all in-text and exercise questions, with an Expert Solution for each. | Class 10 Science Chapter 11 NCERT Solutions |
| Formula Sheet | Quick reference of the must-know formulae, units and combination rules of the chapter. | Class 10 Science Chapter 11 Formula Sheet |
| Handwritten Notes | Scanned-style handwritten pages for last-minute board revision. | Class 10 Science Chapter 11 Handwritten Notes |
| NCERT Book PDF | Official NCERT Science Chapter 11 Electricity textbook in PDF form. | Class 10 Science Chapter 11 NCERT Book PDF |
Notes for Class 10 Science: All Chapters
Related Links: Use the table below to open the revision notes for the other chapters of Class 10 Science. Every chapter ships with the same concept-first notes style, full PDF download, and revision FAQ.
| Chapter | Notes link |
|---|---|
| Chapter 1 | Chemical Reactions and Equations Notes |
| Chapter 2 | Acids, Bases and Salts Notes |
| Chapter 3 | Metals and Non-metals Notes |
| Chapter 4 | Carbon and its Compounds Notes |
| Chapter 5 | Life Processes Notes |
| Chapter 6 | Control and Coordination Notes |
| Chapter 7 | How do Organisms Reproduce? Notes |
| Chapter 8 | Heredity Notes |
| Chapter 9 | Light - Reflection and Refraction Notes |
| Chapter 10 | The Human Eye and the Colourful World Notes |
| Chapter 11 | Electricity Notes (You are here) |
| Chapter 12 | Magnetic Effects of Electric Current Notes |
| Chapter 13 | Our Environment Notes |
Notes Class 10 Science Chapter 11 Electricity FAQs
Ques. What does Chapter 11 Electricity cover in Class 10 Science?
Ans. Chapter 11 covers the flow of electric charge and the energy it carries. The notes explain electric current as the rate of flow of charge, the electric circuit, potential difference, and the ammeter and voltmeter. They then cover Ohm's law and its straight-line V-I graph, resistance and resistivity with the factors that change them, and resistors joined in series and in parallel with the equivalent-resistance formulas. The chapter ends with the heating effect of current and Joule's law, the electric fuse, and electric power and energy measured in kilowatt-hours, all aligned with the 2026-27 CBSE syllabus and with solved numericals.
Ques. What is electric current and in what unit is it measured?
Ans. Electric current is the rate of flow of electric charge through a conductor. If a charge Q crosses any cross-section of a wire in time t, the current is I = Q/t. The SI unit of current is the ampere, written A, where 1 A equals 1 coulomb per second. Current is measured by an ammeter, which is always connected in series in the part of the circuit where the current is to be measured. By convention the direction of current is taken from the positive terminal to the negative terminal in the outer circuit, which is opposite to the direction in which the negatively charged electrons actually drift.
Ques. What is Ohm's law and what does its V-I graph look like?
Ans. Ohm's law states that, at constant temperature, the potential difference V across a conductor is directly proportional to the current I through it, which gives V = IR. The constant R is the resistance of the conductor, measured in ohm. Because V is proportional to I, a graph of V against I for a metal wire at constant temperature is a straight line passing through the origin, and the slope of this line equals the resistance. The law holds only for ohmic conductors such as metal wires at constant temperature; a bulb filament heats up as current rises, so its resistance changes and its V-I graph is a curve, not a straight line.
Ques. How do you combine resistors in series and in parallel?
Ans. In a series combination the resistors lie end to end so the same current flows through each, the voltages add up, and the equivalent resistance is the simple sum R(s) = R1 + R2 + R3, which is larger than any single resistor. In a parallel combination the resistors are joined across the same two points so each has the same voltage, the branch currents add up to the total, and the equivalent resistance is given by 1/R(p) = 1/R1 + 1/R2 + 1/R3, which is always smaller than the smallest resistor. A common mistake is adding parallel resistances directly instead of adding their reciprocals.
Ques. What is Joule's law of heating and where is it used?
Ans. Joule's law of heating says that the heat produced in a resistor is H = I squared R t, which also equals VIt, where I is the current, R the resistance, V the voltage and t the time. So the heat is proportional to the square of the current, to the resistance, and to the time the current flows. This heating effect is used in appliances such as the electric iron, toaster, heater and bulb, where a high-resistance nichrome coil or tungsten filament gets hot. The same law explains the electric fuse, a thin low-melting-point wire placed in series that melts and breaks the circuit if the current rises above a safe value.
Ques. What is electric power and how is electrical energy billed at home?
Ans. Electric power is the rate at which electrical energy is used or supplied, and it can be written in three equal forms: P = VI = I squared R = V squared by R. The SI unit of power is the watt, where 1 W equals 1 volt times 1 ampere, and big appliances are rated in kilowatts. Electrical energy is the power multiplied by the time, E = P t. Because the joule is too small for household use, electricity is sold in kilowatt-hours, called units, where one kilowatt-hour is the energy used when one kilowatt of power runs for one hour, equal to 3.6 multiplied by 10 to the power 6 joules. The monthly meter reads in these units.
Ques. How many pages is the Class 10 Science Electricity Notes PDF?
Ans. The Electricity Notes PDF runs about 20 to 22 pages and covers the full chapter in concept-first revision blocks, with labelled circuit diagrams, the V-I graph, the resistivity table, series and parallel comparison tables, Joule's law and the fuse, the three forms of electric power, the kilowatt-hour, solved numericals, common-mistake boxes, memory aids and a one-glance revision strip. The PDF is free to download for the 2026-27 session, and a green Handwritten Notes button on this page opens the scanned-style version for last-minute revision.
Ques. Are these Notes for Class 10 Science Chapter 11 aligned with the 2026-27 syllabus?
Ans. Yes. This page reflects the current 2026-27 CBSE syllabus for Class 10 Science. The Electricity chapter is part of the current cycle, and these notes follow the NCERT textbook, covering electric current and circuits, potential difference, Ohm's law and the V-I graph, resistance and resistivity, resistors in series and parallel, Joule's law of heating and the electric fuse, and electric power and energy in kilowatt-hours. The notes are written for the CBSE board exam, with the high-frequency question types, the key formulae and the units highlighted throughout.
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