Summary
Electricity is the movement of charges, usually electrons, through a material. For a current to flow you need three things: a source to push it (a battery), a closed path to travel along (the wires) and a device that uses it (a bulb). If the circuit opens, for example with a switch, the current stops.
In a circuit, voltage (volts) is the push the battery gives, current (amperes) is how much charge flows, and resistance (ohms) is what hinders it. Ohm's law links them: V = I · R. Components can be connected in series, one after another on a single path, or in parallel, each on its own path. In series, if one fails they all go out; in parallel, they do not.
Key points
- Electric current is the movement of charges (electrons).
- A circuit needs a source (battery), a closed path (wires) and a device (bulb).
- Voltage (V, volts), current (I, amperes) and resistance (R, ohms).
- Ohm's law: V = I × R.
- Materials can be conductors (metals) or insulators (plastic).
- In series, everything is on one path: if one fails, all go out.
- In parallel, each has its own path: the rest keep working if one fails.