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By the end of this topic, you should be able to:
Electric current is the flow of charge carriers through a material.
Think of it like water flowing through a pipe — except instead of water molecules, we have charged particles moving through a wire.
A charge carrier is any particle that carries an electric charge and can move through a material. Charge carriers can be:
In a metal wire, the charge carriers are free electrons — electrons that are not attached to any particular atom and are free to drift through the metal.
When you connect a wire to a battery or power supply, a potential difference (voltage) is created across the wire. This acts like a push, causing charge carriers to flow in a particular direction. That flow of charge is what we call electric current.
This is one of the most important — and most confusing — ideas in electricity. Pay close attention.
In a metal wire:
Before scientists discovered the electron, they assumed current was the flow of positive charge. They defined current as flowing from positive to negative. This became the conventional current direction and is still used today.
| Direction | |
|---|---|
| Electron flow | Negative terminal → Positive terminal |
| Conventional current | Positive terminal → Negative terminal |
⚠️ These two directions are opposite to each other. In your exam, always use the conventional current direction (positive to negative) unless asked specifically about electron flow.
Current is measured using an ammeter (a device that measures current in amperes). An ammeter must always be connected in series — meaning the current must actually flow through it.
The unit of current is the ampere (A), also called an "amp."
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