Current - GCSE Physics Definition

What is current?

In GCSE Physics, current is the flow of charge per unit time. The charge carriers in an electrical circuit are the free electrons that flow around the circuit when a potential difference or voltage is introduced. Each electron has a charge; the amount of charge passing a fixed point in a circuit per unit time is the current. 

Current is measured in amperes, or amps (A) by an ammeter. Ammeters must be placed in series to allow the current to flow through. 

Current is the same everywhere in a series circuit because there is only one path for the electrons to flow through. 

In a parallel circuit, the current is different at different places in the circuit. This is because the electrons have more than one path they can take. The sum of the current in the individual branches is always equal to the total current of the circuit.

Conventional current flows the opposite way around a circuit to the negative electrons. When electricity was first widely used, it was believed that positive charge flowed from the positive terminal to the negative terminal, which gave rise to the idea of conventional current. When electrons were discovered, it was found that it is actually the negative electrons that flow, but the concept of conventional current is still used today.

Conventional current flows in the direction that a positive charge would flow around a circuit, from the positive terminal to the negative terminal. 

Electron flow shows the direction that electrons actually do flow around a circuit: from the negative terminal to the positive terminal.

All specifications and exam questions use ‘current’ to mean conventional current. 

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