Class 10 Science Chapter 11 (formerly Chapter 12), Electricity, develops electric current, potential difference, Ohm’s law, resistivity, series and parallel resistor networks, Joule’s law of heating, and electric power and commercial energy billing.
What Class 10 Science Chapter 11 Covers
11.1 to 11.5 Electric Current, Potential Difference, Circuit Diagrams, Ohm’s Law & Resistivity defines electric current $I = \frac{Q}{t}$ (in amperes, $1\text{ C} \approx 6\times 10^{18}$ electrons) measured by an ammeter in series, potential difference $V = \frac{W}{Q}$ (in volts) measured by a voltmeter in parallel, Ohm’s law $V = IR$, and resistance $R = \rho\frac{l}{A}$ where $\rho$ is electrical resistivity ($\Omega\text{ m}$), explaining why alloys like nichrome have higher resistivity and do not oxidise readily at high temperatures.
11.6 Resistance of a System of Resistors derives the equivalent resistance for resistors in series ($R_s = R_1 + R_2 + R_3$) and resistors in parallel ($\frac{1}{R_p} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}$), and explains why domestic appliances are connected in parallel rather than in series.
11.7 & 11.8 Heating Effect of Electric Current & Electric Power derives Joule’s law of heating $H = I^2Rt$ (applied to electric irons, toasters, tungsten-filament bulbs at $3380^\circ\text{C}$, and fuse wires made of lead-tin alloy), defines electric power $P = VI = I^2R = \frac{V^2}{R}$ (in watts), and relates the commercial unit of electrical energy $1\text{ kWh} = 3.6\times 10^6\text{ J}$.
Exercises in Chapter 11
- In-text Questions cover calculating the number of electrons constituting $1\text{ coulomb}$ of charge, how the resistance of a wire changes when its length or cross-sectional area changes, and the advantages of connecting electrical devices in parallel with the battery instead of in series.
- Chapter Exercises (18 Questions) test equivalent resistance combinations (such as cutting a wire of resistance $R$ into five equal parts and connecting them in parallel to get $R/25$), Joule heating calculations, and household energy bills in $\text{kWh}$.
Read Class 10 Science Chapter 11 Online
More Chapters
- Previous: Chapter 10: The Human Eye and the Colourful World
- Next: Chapter 12: Magnetic Effects of Electric Current
- Hindi medium: Class 10 Science Chapter 11 PDF in Hindi (Vigyan)
- All Science chapters and the other Class 10 books: Class 10 NCERT books 2026-27
- All Class 1 to 12 NCERT Textbooks: NCERT Books PDF (Class 1–12)
FAQ
Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?
Alloys (such as nichrome) have a much higher resistivity than their constituent pure metals, and they do not oxidise (burn) readily at high temperatures.
Why is the series arrangement not used for domestic circuits?
In a series circuit, if one appliance stops working the entire circuit is broken; all appliances cannot be operated independently with separate switches; and devices with different current ratings (like a bulb and a heater) cannot receive the same $220\text{ V}$ voltage they need.