Chapter 11 — Electricity

NCERT Class 10 Science Chapter 11 covers Electricity — the flow of electric charge through conductors, governed by Ohm's law (V = IR), resistance, series and parallel circuits, Joule's heating effect (H = I²Rt), and electric power (P = VI).

Chapter 11 of NCERT Class 10 Science explores electricity in depth. Electric current (I = Q/t) is measured in amperes using an ammeter. Potential difference, measured in volts by a voltmeter, drives current through a circuit. Ohm's law states V = IR, where resistance R (in ohms) depends on the conductor's length, cross-sectional area, and material resistivity. Resistors in series add directly (Rs = R1 + R2 + R3), while parallel combinations follow 1/Rp = 1/R1 + 1/R2 + 1/R3. The heating effect of current is given by Joule's law H = I²Rt, with applications in electric heaters, bulbs, and fuses. Electric power P = VI = I²R = V²/R is measured in watts; the commercial unit of energy is kilowatt hour (1 kWh = 3.6 × 10⁶ J).

1. 01Electric current I = Q/t is measured in amperes (A); 1 coulomb of charge equals the charge of approximately 6 × 10¹⁸ electrons.
2. 02Ohm's law: potential difference V across a conductor is directly proportional to current I at constant temperature, expressed as V = IR.
3. 03Resistance R = ρl/A; resistivity ρ (in Ω m) depends on the material — metals have resistivity 10⁻⁸ to 10⁻⁶ Ω m, insulators 10¹² to 10¹⁷ Ω m.
4. 04In a series circuit, equivalent resistance Rs = R1 + R2 + R3 and the same current flows through all resistors; in a parallel circuit, 1/Rp = 1/R1 + 1/R2 + 1/R3 and the same potential difference appears across each resistor.
5. 05Joule's law of heating: H = I²Rt — heat produced is proportional to the square of current, resistance, and time; this principle powers electric heaters, irons, and fuses.
6. 06Electric power P = VI = I²R = V²/R in watts (W); commercial electrical energy is measured in kilowatt hours (1 kWh = 3.6 × 10⁶ J).