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Electrical terms: what do they mean?!

Electrical terms: what do they mean?!Confused by current? Vexed by voltage? We’ve put together a handy checklist to help you tell the difference.

Current vs voltage

Current refers to the flow of electricity around a circuit, whereas voltage refers to the power within the circuit. It is easiest to imagine with a couple of examples.

Think of a circuit which contains a battery, a switch, and a light bulb. In order for the bulb to light up, it needs to have both current and voltage. The voltage is contained within the battery, and will always be there whether the switch is open or closed. However, when the switch is open, the electricity cannot flow around the circuit, so there is no current.

Voltage is the energy. It is carried around the circuit and used up in components. When the light bulb goes on, some of the energy in the voltage is turned into light and heat.

Current is the rate the charge flows round the circuit. It is not used up, but can go up or down depending on the resistance of the circuit.

a.c. vs d.c.

It doesn’t matter whether it’s low or high voltage, a.c. and d.c. refer to the current flowing around a circuit.

Direct current (d.c.) flows in one direction, usually from positive to negative. Batteries are a source of direct current.

Alternating current (a.c.) continuously changes direction. The current that flows through plug sockets in your house is an alternating current – the direction of the flow changes 50 times per second.

Conductor vs Semiconductor

A conductor is a material that allows electricity to flow through it very well in either direction. Many metals conduct electricity, and so are good choices for making things like wires.

A semiconductor is a material that allows electricity to flow very strongly in one direction, but only weakly in another direction. Semiconductors are made from materials that do not usually conduct electricity, such as silicon. When silicon is combined with certain chemicals, it becomes a semiconductor.

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