Electricity
Physics · विद्युत
📋Quick Overview
Electricity is the flow of electric charge (electrons) through a conductor. Current electricity powers our homes, phones, and everything electronic. The key concepts are: Current (I) = flow of charge, Voltage (V) = push/pressure that drives current, Resistance (R) = opposition to current flow. These three are connected by Ohm's Law: V = IR.
📖Current, Voltage & Resistance
| Quantity | Symbol | Formula | SI Unit | Analogy |
|---|---|---|---|---|
| Current | I | I = Q/t (charge per second) | Ampere (A) | Water flow in a pipe |
| Voltage | V | V = W/Q (work per charge) | Volt (V) | Water pressure in pipe |
| Resistance | R | R = V/I (Ohm's Law) | Ohm (Ω) | Narrow pipe restricts flow |
⭐
Ohm's Law: V = IR. This means: Current is directly proportional to voltage and inversely proportional to resistance. Double the voltage = double the current. Double the resistance = half the current.
📖Series vs Parallel Circuits
📖Electric Power & Household Electricity
- •Power = P = VI = I²R = V²/R. SI unit = Watt (W). 1 kW = 1000 W.
- •Electric Energy = P × t. Electricity bill measured in kWh (1 kWh = 1 'unit').
- •Household wiring is PARALLEL — each appliance gets same voltage (220V in India) and works independently.
- •FUSE: Thin wire that melts and breaks circuit if current exceeds safe limit. Prevents fire. Always in LIVE wire.
- •EARTHING: Connecting metal body of appliance to ground. If leakage current flows, it goes to earth (not through your body). Safety measure.
- •LED: Light Emitting Diode — uses very less power, long life, no heat. Most energy efficient lighting.
- •3 wires in household: Live (Red/Brown), Neutral (Black/Blue), Earth (Green/Yellow-green)