How it works
Ohm's law says current through a conductor is voltage divided by resistance. Voltage is the electrical 'pressure', resistance the narrowness of the pipe, and current the resulting flow. Three quantities, one triangle, all of electronics.
Combine it with the power law (P = VI) and you can size fuses, understand why extension cords have thickness ratings, and see why high-voltage transmission lines exist: raising voltage lets the grid deliver the same power at lower current, slashing resistive losses (which grow with I²).
Every appliance label is Ohm's law in disguise. A 2,300 W kettle on a 230 V outlet must draw 10 A — which is why running it together with a heater can trip a 16 A breaker.
Use it in real life
Home safety: a 16 A circuit at 230 V can safely supply ~3,680 W. Add up the wattage of what's plugged in — physics tells you when the breaker will trip before it does.
EV charging: a home wallbox at 230 V and 16 A delivers ~3.7 kW; a three-phase 32 A unit ~22 kW. Charge-time estimates are just Ohm's law plus battery capacity.
Electronics repair: measuring resistance across a component and applying V = IR is the first diagnostic step for practically every hardware fault.
Frequently asked questions
What are volts, amps and ohms in plain language?
Volts are electrical pressure, amps the flow rate of charge, and ohms the resistance to that flow. Pressure ÷ resistance = flow: that's Ohm's law.
Why is high current dangerous rather than high voltage?
Physiologically it's current through the body that harms — as little as 0.03–0.1 A across the heart. Voltage matters because it's what pushes current through your body's resistance (I = V/R).
Does Ohm's law apply to all components?
It holds for resistive conductors (wires, heaters, filament bulbs). Diodes, LEDs and transistors are non-ohmic — their current-voltage relationship is a curve, not a straight line.