Usesanother area
Data handlingA family's monthly electricity use varies; the mean, median and range of a year of bills show what is typical.
Physics · Electricity and magnetismTechnology · Engineering and power
Electricity
What actually happens between the power station and the switch under your finger?
Electricity is charge on the move. Learn what pushes it, what resists it, how it is made and delivered, what it costs, and how to stay safe around it.
5 depths≈ 185 min of reading
The ladder
Choose how deep to go
Every depth is open. Start where it feels interesting — you can always move back.
- Discoverabout 35 minElectricity is charge on the moveMeet the charges hiding in every atom, see why a doorknob spark and lightning are the same idea, discover why slow electrons still light a bulb instantly, build circuits that break, and learn the first rules for staying safe.Owner-accepted · not line-by-line reviewed
- Understandabout 35 minThe big three: voltage, current, resistanceBuild the pump-and-pipe picture of a circuit, then meet voltage (the push), current (the flow) and resistance (the pushback) with real numbers from AA cells to lightning. Finish with Ohm's law, V = I × R, and the mix-ups it clears up.Owner-accepted · not line-by-line reviewed
- Investigateabout 40 minCircuits you can testDesign fair circuit tests, place ammeters and voltmeters correctly, compare series and parallel bulbs, test Ohm's law and see a filament bulb break it, work out when an MCB trips, and build a safe lemon battery.Owner-accepted · not line-by-line reviewed
- Go deeperabout 35 minHow it's made and how it reaches youFollow electricity from a spinning magnet in a power station, through transformers and 765 kV lines, down to the 230 V socket in your room. Learn why the grid runs on AC at 50 Hz, why it transmits at high voltage, and why supply must match demand every second.Owner-accepted · not line-by-line reviewed
- Extendabout 40 minPower, bills, safety and the futureUse P = V × I and E = P × t to read rating plates and work out a real electricity bill in units (kWh). Learn why current through the body is what injures, how earth pins, MCBs and RCCBs protect you, what to do in a shock emergency, and how solar, storage and smart meters are changing the grid.Owner-accepted · not line-by-line reviewed
The web
Connected ideas
Follow a connection when you’re curious — some lead into completely different areas.
Electricity
Usesanother area
Number systemPower stations are rated in megawatts and India uses lakhs of crores of units a year: reading such numbers needs place value and the Indian system.
Usesanother area
Four operationsAn electricity bill is units × rate per unit, plus fixed charges, minus subsidies — all four operations in one sheet of paper.
Usesanother area
AnglesA generator's coil turns through 360° every cycle — 50 full turns a second on India's 50 Hz supply.
Usesanother area
Prime and composite numbersThe encryption that protects smart meters and grid control systems relies on the difficulty of factorising huge numbers into primes.