Electricity powers our world, from lights to gadgets, through the flow of electric charges like electrons. This CBSE Class 10 chapter breaks down key concepts like current, voltage, resistance, and circuits for easy understanding.
Electric Current Basics
Electric current (I) is the rate of charge (Q) flow, measured in amperes (A): I = Q/t. Potential difference (V), or voltage, drives this flow, like water pressure in pipes, in volts (V). Resistance (R) opposes flow, depending on material, length, area, and temperature; resistivity (ρ) is material-specific.
Ohm's Law
Ohm's Law states V = I × R, linking voltage, current, and resistance linearly at constant temperature. A simple circuit with battery, ammeter, voltmeter, and rheostat verifies this: plot V vs. I for a straight line. Factors affecting resistance: R = ρL/A.
Resistors in Circuits
In series, total R = R₁ + R₂ + ...; same current flows through each. In parallel, 1/R_total = 1/R₁ + 1/R₂ + ...; voltage is same across branches. Mixed circuits simplify by combining series/parallel step-by-step.
| Combination | Total Resistance | Current/Voltage |
|---|---|---|
| Series | Sum increases | Same I, V adds |
| Parallel | Sum decreases | Same V, I adds |
Power and Energy
Electric power P = V × I = I²R = V²/R, in watts (W); 1 kW = 1000 W. Energy E = P × t, in kWh for billing. Example: A 100W bulb for 10 hours uses 1 kWh.
Heating Effect
Current heats conductors via Joule's Law: H = I²Rt, used in fuses (melt at overload), heaters, bulbs. Safety devices like fuses break circuits to prevent fires.
Master these for exams—practice numericals on Ohm's Law and circuits for top scores.
