Electricity basics for beginners
New to electronics? These six ideas are all you need before the first lesson.
1 · Everything is made of charge
Metal wires are full of tiny charged particles (electrons) that can move. A battery does not add new ones; it pushes the ones that are already there.
2 · Voltage is the push
Voltage is the difference in electrical "pressure" between two points, measured in volts (V). It is always measured between two points — usually from ground.
3 · Current is the flow
Current is how much charge flows past a point each second, measured in amps (A). It only flows if there is a complete loop: a circuit.
4 · Resistance limits the flow
Resistance (ohms, Ω) sets how much current a voltage can push through: I = U ÷ R. That is Ohm’s law, the most-used rule in electronics.
5 · Power is how hard it is working
Power = voltage × current, in watts (W). In a resistor all of it becomes heat. Every part has a rating — exceed it and it burns.
6 · Current is not used up
The same current that leaves the battery comes back to it. What the parts use up is energy: the push (voltage) drops across each part, while the flow stays the same all the way round.
The water analogy
| Electricity | Water | Meaning |
|---|---|---|
| Battery | Pump | Creates the pressure difference |
| Voltage (V) | Water pressure | How hard it pushes |
| Current (A) | Litres per second | How much flows |
| Resistor (Ω) | Narrow pipe | Limits the flow |
| Wire | Wide pipe | Almost no resistance |
| Switch | Valve | Opens or closes the loop |
| Capacitor | Tank with a rubber wall | Stores some, then gives it back |
| Diode | One-way flap valve | Only lets flow go one way |