Complete Solutions and Summary of Electricity – NCERT Class 10, Science, Chapter 11 – Summary, Questions, Answers, Extra Questions

Comprehensive summary and explanation of Chapter 11 'Electricity', covering fundamentals of electric current, electric circuits, Ohm’s law, resistance, resistivity, factors affecting resistance, series and parallel combinations of resistors, heating effect of electric current, electric power, energy consumption, and all solved NCERT questions and extra practice questions from Class X Science.

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Categories: NCERT, Class X, Science, Physics, Summary, Extra Questions, Electricity, Circuits, Ohm’s Law, Resistance, Power, Heating Effect, Chapter 11

Tags: Electricity, Electric Current, Potential Difference, Electric Circuit, Ohm’s Law, Resistance, Resistivity, Series Combination, Parallel Combination, Heating Effect, Electric Power, Energy, Ammeter, Voltmeter, Joule’s Law, NCERT, Class 10, Science, Chapter 11, Answers, Extra Questions

Electricity Class 10 NCERT Chapter 11 - Ultimate Study Guide, Notes, Questions, Quiz 2025

Full Chapter Summary & Detailed Notes - Electricity Class 10 NCERT

Overview & Key Concepts

Chapter Goal: Understand electricity, current flow, potential difference, Ohm's law, resistance factors. Exam Focus: Calculations, circuits, applications. 2025 Updates: Links to energy, safety. Fun Fact: Electrons flow opposite to current direction. Core Idea: Controllable energy form. Real-World: Homes, industries use.
Wider Scope: Power, electronics, safety.

Introduction

Important in society; controllable energy for homes, schools, hospitals, industries.
Questions: What is electricity? How flows in circuit? Factors regulating current? Heating effect applications.

11.1 Electric Current and Circuit

Like air/water current; charge flow through conductor is current.
Torch: Cells provide current through bulb; switch links.
Closed path: Electric circuit; broken stops flow.
Current: Charge rate (I = Q/t); coulomb/second = ampere.
Coulomb: Charge of 6 x 10^18 electrons; ampere 1 C/s.
Ammeter: Measures current, series connected.
Direction: Positive charges; opposite to electrons.

Example 11.1

0.5 A for 10 min: Q = 300 C.

Questions

1. Continuous closed path of current.
2. Ampere: 1 C/s.
3. 6 x 10^18 electrons.

11.2 Electric Potential and Potential Difference

Like water flow from pressure; charges need potential difference.
Battery produces difference via chemical action.
Definition: Work per unit charge (V = W/Q); volt = joule/coulomb.
1 V: 1 J to move 1 C.
Voltmeter: Measures difference, parallel connected.

Example 11.2

2 C at 12 V: W = 24 J.

Questions

1. Cell/battery.
2. 1 J work for 1 C charge.
3. 6 J per coulomb.

11.3 Circuit Diagram

Schematic with symbols for components.
Table: Cell, battery, switch open/closed, wire joint, crossing, bulb, resistor, variable resistance, ammeter, voltmeter.

11.4 Ohm’s Law

Relation: Potential difference and current.
Activity 11.1: Nichrome wire, cells; V/I constant; graph straight line.
Law: V proportional to I at constant temperature; V = IR.
Resistance: Property resisting flow; ohm = 1 V/1 A.
Current inverse to resistance.
Rheostat: Varies resistance.

Activity 11.2

Different components: Nichrome, bulbs; currents vary; resistance differs.

11.5 Factors on which the Resistance of a Conductor Depends

Activity 11.3: Length, area, material affect current/resistance.
R proportional to length, inverse to area; R = ρ l / A.
Resistivity: Constant for material; ohm-metre.
Metals low resistivity; insulators high.
Alloys higher; used in heaters.
Table: Conductors (silver, copper), alloys (constantan), insulators (glass, rubber).
Varies with temperature.

Example 11.3

Bulb 1200 Ω at 220 V: 0.18 A; heater 100 Ω: 2.2 A.

Why This Guide Stands Out

Complete chapter coverage: Notes, activities, Q&A (all NCERT + extras), quiz. Student-centric, exam-ready for 2025. Free & ad-free.

Key Themes & Tips

Current: Charge flow rate.
Ohm's Law: V=IR.
Resistance: Depends on l, A, material.
Tip: Practice calculations; draw circuits.

Exam Case Studies

Current calculations; resistance factors; circuit diagrams.

Project & Group Ideas

Build simple circuits; test resistance materials; discuss energy safety.

Key Definitions & Terms - Complete Glossary

All terms from chapter; easy to memorize.

Electric Current

Electric current is the rate of flow of electric charge through a conductor. It is measured as the amount of charge passing per unit time, with electrons as charge carriers in metals. Example: In a wire, current flows when a battery is connected, lighting a bulb.

Electric Circuit

An electric circuit is a continuous and closed path for electric current. It includes components like cell, bulb, switch, and wires; current stops if broken. Example: Torch circuit with battery, bulb, and switch.

Coulomb

Coulomb is the SI unit of electric charge, equal to charge of about 6 x 10^18 electrons. It quantifies charge amount; 1 C = 1 A * 1 s. Example: Charge flowing in 1 second at 1 ampere current.

Ampere

Ampere is the SI unit of electric current, 1 coulomb per second. It measures flow rate; smaller units like milliampere (10^-3 A). Example: Bulb drawing 0.5 A for 10 minutes passes 300 C.

Potential Difference

Potential difference is work done to move unit charge between points. Measured in volts; drives current like pressure drives water. Example: 12 V between points means 12 J for 1 C charge.

Volt

Volt is the SI unit of potential difference, 1 joule per coulomb. 1 V means 1 J work for 1 C charge. Example: Battery providing 6 V gives 6 J per coulomb.

Ammeter

Ammeter is an instrument measuring electric current in a circuit. Connected in series; low resistance. Example: In circuit with bulb, shows current flow.

Voltmeter

Voltmeter measures potential difference between points. Connected in parallel; high resistance. Example: Across bulb, shows voltage drop.

Ohm's Law

Ohm's law states potential difference proportional to current at constant temperature. V = IR; resistance constant. Example: Graph of V vs I is straight line.

Resistance

Resistance is property opposing charge flow. Unit ohm; R = V/I. Example: Bulb filament with high resistance heats up.

Ohm

Ohm is SI unit of resistance, 1 volt per ampere. 1 ohm allows 1 A at 1 V. Example: Wire with 1 ohm needs 1 V for 1 A.

Rheostat

Rheostat is variable resistance to regulate current. Changes resistance without altering voltage. Example: Dimmer switch varying bulb brightness.

Resistivity

Resistivity is material property measuring resistance per unit length and area. Unit ohm-metre; ρ = R A / l. Example: Copper low resistivity, good conductor.

Conductor

Conductor allows easy charge flow, low resistance. Metals like copper; electrons move freely. Example: Wires in circuits.

Insulator

Insulator resists charge flow, high resistance. Like rubber, glass; electrons bound. Example: Wire coatings prevent shocks.

Resistor

Resistor is component with specific resistance. Controls current; offers appreciable opposition. Example: In circuits to limit flow.

Alloy

Alloy is metal mixture with higher resistivity than pure metals. Used in heaters; resists oxidation. Example: Nichrome in irons.

Variable Resistance

Variable resistance changes current without voltage change. Adjusts flow; like rheostat. Example: Volume control in radios.

Tip: Use flashcards; associate with examples.

60+ Questions & Answers - NCERT Based (Class 10)

Structured as Part A (1 mark, short answers), Part B (4 marks, ~6 lines answers), Part C (8 marks, detailed). 20 per part, based on content questions/exercises/content.

Part A: 1 Mark Questions (Short Answers)

1. What does an electric circuit mean?

1 Mark Answer: Closed path.

2. Define the unit of current.

1 Mark Answer: Ampere.

3. Calculate the number of electrons constituting one coulomb of charge.

1 Mark Answer: 6 x 10^18.

4. Name a device that helps to maintain a potential difference across a conductor.

1 Mark Answer: Cell.

5. What is meant by saying that the potential difference between two points is 1 V?

1 Mark Answer: 1 J/C.

6. How much energy is given to each coulomb of charge passing through a 6 V battery?

1 Mark Answer: 6 J.

7. What is electric current?

1 Mark Answer: Charge flow.

8. What is the SI unit of charge?

1 Mark Answer: Coulomb.

9. How is ammeter connected?

1 Mark Answer: Series.

10. What is potential difference?

1 Mark Answer: Work/charge.

11. How is voltmeter connected?

1 Mark Answer: Parallel.

12. State Ohm's law.

1 Mark Answer: V=IR.

13. What is resistance?

1 Mark Answer: V/I.

14. Unit of resistance?

1 Mark Answer: Ohm.

15. What is rheostat?

1 Mark Answer: Variable resistance.

16. Factor affecting resistance: length?

1 Mark Answer: Proportional.

17. Factor: area?

1 Mark Answer: Inverse.

18. What is resistivity?

1 Mark Answer: Material constant.

19. Unit of resistivity?

1 Mark Answer: Ohm-metre.

20. Best conductor?

1 Mark Answer: Silver.

Part B: 4 Marks Questions (Answers in ~6 Lines)

1. What does an electric circuit mean?

4 Marks Answer: Continuous closed path for current. Includes cell, bulb, switch, wires. Current flows when closed. Broken stops flow. Like torch circuit. Essential for devices.

2. Define the unit of current.

4 Marks Answer: Ampere: 1 coulomb per second. Named after Ampere. Milliampere 10^-3 A. Measures flow rate. Ammeter uses. 1 A = 6 x 10^18 electrons/s.

3. Calculate the number of electrons constituting one coulomb of charge.

4 Marks Answer: Electron charge 1.6 x 10^-19 C. Number = 1 / 1.6 x 10^-19. Equals 6.25 x 10^18. Approx 6 x 10^18. Negative charges. Flow opposite current.

4. Name a device that helps to maintain a potential difference across a conductor.

4 Marks Answer: Cell or battery. Chemical action creates difference. No current drawn still present. Expends energy for current. Like water tank pressure. Volta discovered.

5. What is meant by saying that the potential difference between two points is 1 V?

4 Marks Answer: 1 joule work for 1 coulomb charge. V = W/Q. Named after Volta. Voltmeter measures. Drives current. 1 V = 1 J/C.

6. How much energy is given to each coulomb of charge passing through a 6 V battery?

4 Marks Answer: W = V Q. For 1 C, 6 J. Battery provides. Chemical to electrical. Voltmeter shows. Energy per charge.

7. A current of 0.5 A is drawn by a filament of an electric bulb for 10 minutes. Find the amount of electric charge that flows through the circuit.

4 Marks Answer: Q = I t. t = 600 s. Q = 0.5 x 600 = 300 C. Coulomb unit. Charge flow. Bulb filament.

8. How much work is done in moving a charge of 2 C across two points having a potential difference 12 V?

4 Marks Answer: W = V Q. 12 x 2 = 24 J. Joule unit. Energy transfer. Potential work. Conductor points.

9. What is the direction of conventional current?

4 Marks Answer: Positive to negative. Opposite electrons. Historical. Positive charges. Circuit from + terminal. Ammeter shows.

10. What is Ohm's law?

4 Marks Answer: V proportional I, constant T. V=IR. R constant. Graph linear. Ohm discovered. Resistance defines.

11. What is resistance?

4 Marks Answer: Opposes flow. R=V/I. Ohm unit. Material property. Electrons restrained. Conductor size affects.

12. What factors affect resistance?

4 Marks Answer: Length proportional. Area inverse. Material resistivity. Temperature varies. R=ρ l/A. Experiments show.

13. What is resistivity?

4 Marks Answer: Material constant. ρ=R A/l. Ohm-m unit. Metals low. Alloys high. Temperature dependent.

14. Why alloys used in heaters?

4 Marks Answer: High resistivity. No oxidation high T. Nichrome example. Constituent metals lower. Tungsten bulbs. Copper transmission.

15. What is a conductor?

4 Marks Answer: Low resistance. Free electrons. Metals like silver. Flow easy. Circuits use. Opposite insulator.

16. What is an insulator?

4 Marks Answer: High resistance. Bound electrons. Glass, rubber. No flow. Safety coatings. High resistivity.

17. What is a resistor?

4 Marks Answer: Appreciable resistance. Controls current. Fixed value. Circuits limit. Poor conductor. Size identical.

18. What is rheostat?

4 Marks Answer: Variable resistance. Regulates current. No voltage change. Circuits adjust. Slider type. Practical use.

19. How does length affect resistance?

4 Marks Answer: Directly proportional. Double length, double R. Path longer. Electrons more collisions. Experiment shows. R ∝ l.

20. How does area affect resistance?

4 Marks Answer: Inversely proportional. Thicker wire, less R. More paths. Fewer collisions. Experiment thicker wire. R ∝ 1/A.

Part C: 8 Marks Questions (Detailed Answers)

1. What does an electric circuit mean?

8 Marks Answer: An electric circuit is a continuous and closed path through which electric current flows. It consists of components like a cell or battery as the source, conducting wires, an electrical component such as a bulb, and a switch to control the flow. When the switch is on, the circuit is complete, allowing charges to flow from the positive terminal of the cell through the bulb and back to the negative terminal. If the circuit is broken anywhere, such as by turning off the switch, the current stops, and the bulb does not glow. This setup is essential for the functioning of electrical devices, as seen in a torch where cells provide the flow of charges to make the bulb glow. The concept is analogous to water flowing in a closed pipe system.

2. Define the unit of current.

8 Marks Answer: The unit of current is ampere (A), defined as the flow of one coulomb of charge per second through a conductor. It is named after the French scientist Andre-Marie Ampere. One ampere corresponds to approximately 6 x 10^18 electrons passing a point per second, since each electron carries a charge of 1.6 x 10^-19 C. Smaller units include milliampere (1 mA = 10^-3 A) and microampere (1 µA = 10^-6 A) for low currents. Current is measured using an ammeter connected in series in the circuit. The direction of conventional current is from positive to negative terminal, opposite to the electron flow.

3. Calculate the number of electrons constituting one coulomb of charge.

8 Marks Answer: The charge on one electron is 1.6 x 10^-19 C. To find the number of electrons in one coulomb, divide 1 by 1.6 x 10^-19, which gives 6.25 x 10^18 electrons. Approximately, it is taken as 6 x 10^18 electrons. This calculation shows the vast number of electrons needed for even a small charge. Electrons are negative charges, and their flow constitutes current in metallic wires, though conventionally current direction is opposite. This is fundamental to understanding charge flow in circuits.

4. Name a device that helps to maintain a potential difference across a conductor.

8 Marks Answer: A cell or battery maintains potential difference across a conductor. A cell generates potential difference through chemical reactions inside it, creating a difference even without current draw. When connected to a circuit, it sets charges in motion, producing current. A battery is a combination of cells. This difference is like pressure in water flow. The energy stored chemically is expended to maintain flow. Alessandro Volta invented the voltaic cell, leading to the unit volt.

5. What is meant by saying that the potential difference between two points is 1 V?

8 Marks Answer: A potential difference of 1 V means 1 joule of work is done to move 1 coulomb of charge from one point to the other. It is defined as V = W/Q, where W is work in joules and Q is charge in coulombs. This unit is named after Alessandro Volta. Voltmeter measures it in parallel. Potential difference drives current, similar to pressure difference driving water. In a conductor, it sets electrons in motion.

6. How much energy is given to each coulomb of charge passing through a 6 V battery?

8 Marks Answer: The energy given is 6 joules per coulomb. From V = W/Q, for Q=1 C, W=6 J. The battery converts chemical energy to electrical potential energy. This work moves the charge. Voltmeter shows 6 V. In circuits, this energy lights bulbs or runs devices.

7. A current of 0.5 A is drawn by a filament of an electric bulb for 10 minutes. Find the amount of electric charge that flows through the circuit.

8 Marks Answer: Use Q = I t. I=0.5 A, t=10 min=600 s. Q=0.5 x 600=300 C. This charge flows through the filament, heating it to glow. Coulomb is unit. Shows rate application. In metals, electrons carry charge.

8. How much work is done in moving a charge of 2 C across two points having a potential difference 12 V?

8 Marks Answer: W = V Q =12 x 2=24 J. Joule is work unit. Potential difference does work. Energy from source. In circuit, converts to heat/light. Volta defined.

9. On what factors does the resistance of a conductor depend?

8 Marks Answer: Resistance depends on length (proportional), cross-sectional area (inverse), material (resistivity), and temperature. R = ρ l / A, where ρ is resistivity. Longer wire increases collisions; thicker reduces. Different materials have varying ρ; metals low, alloys high. Temperature increases resistance in metals. Experiments with nichrome wires confirm. Essential for wire choice in applications.

10. Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?

8 Marks Answer: Thick wire; lower resistance. R inverse to area. Larger area, more paths for electrons, fewer collisions. Same material, length, temperature. Experiment: Thicker nichrome higher current. Practical: Transmission lines thick. Thin wire heats more.

11. Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?

8 Marks Answer: Alloys have higher resistivity; produce more heat. Do not oxidize at high temperatures. Pure metals lower resistivity, melt easily. Nichrome alloy of Ni, Cr, Mn, Fe. Table shows alloys like constantan 49 x 10^-6 ohm-m vs copper 1.62 x 10^-8. Used in heating devices.

12. Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5 Ω resistor, an 8 Ω resistor, and a 12 Ω resistor, and a plug key, all connected in series.

8 Marks Answer: Diagram: Battery (three cells), series resistors 5Ω, 8Ω, 12Ω, plug key. Symbols: Battery long-short lines, resistors zigzag, key circle. Total R=25Ω. Current flows when key closed. Equivalent to single resistor. Calculate current if needed.

13. What is the nature of V-I graph for ohmic conductors?

8 Marks Answer: Straight line through origin. V proportional I. Slope = R. Constant ratio. Activity with nichrome shows. Non-ohmic deviate. Confirms Ohm's law at constant T.

14. How does resistance change with temperature?

8 Marks Answer: Increases in metals; varies. More vibrations, collisions. Alloys less change. Insulators decrease. Practical: Bulb filament heats, resistance rises. Affects calculations.

15. Why is tungsten used in bulbs?

8 Marks Answer: High melting point, resistivity. Glows white hot without melting. Low vaporization. Alloys not suitable. Resistivity 5.20 x 10^-8 ohm-m. Filaments coiled.

16. Explain the activity to study factors affecting resistance.

8 Marks Answer: Circuit with cell, ammeter, nichrome wire l. Note current. Double length: Current halves, R doubles. Thicker wire: Current increases, R decreases. Copper wire: Higher current, lower R. Shows length, area, material effects.

17. What is the difference between conductor and resistor?

8 Marks Answer: Conductor low resistance, easy flow; resistor appreciable resistance, limits flow. Same size: Conductor good, resistor poor. Insulator higher. Electrons free in conductors, restrained in resistors. Applications differ.

18. Explain Ohm's law experiment.

8 Marks Answer: Nichrome wire, ammeter, voltmeter, cells. One cell: Note I, V. Add cells: V/I constant. Graph linear origin. Shows V ∝ I. Constant R. Temperature same.

19. How much current will an electric bulb draw from a 220 V source, if the resistance of the bulb filament is 1200 Ω?

8 Marks Answer: I = V/R = 220/1200 = 0.18 A. Ohm's law. Bulb filament high R. Compared to heater 2.2 A at 100 Ω. Shows inverse relation. Practical power calculation.

20. How much current will an electric heater coil draw from a 220 V source, if the resistance of the heater coil is 100 Ω?

8 Marks Answer: I = 220/100 = 2.2 A. Higher current than bulb. Low R more flow. Heating effect. Alloys used. Demonstrates application.

Practice Tip: Time yourself; use formulas for long Q.

Component	Symbol
Electric cell	Long-short line
Battery	Multiple cells
Switch open	Break in line
Switch closed	Connected line
Wire joint	Dot
Wires crossing	No join
Electric bulb	Circle with filament
Resistor R	Zigzag
Variable resistance	Zigzag with arrow
Ammeter	A in circle
Voltmeter	V in circle

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