Series and parallel circuits
Jonny Nelson introduces an animated explanation of circuits
A A circuit where one component follows directly from another, eg three bulbs in a row with no junctions are said to be connected in series. A closed loop through which current moves - from a power source, through a series of components, and back into the power source. only has one loop. The Moving electric charges, eg electrons moving through a metal wire. flowing can be measured with an A device used to measure electric current. connected in series in the circuit.
Learn more on series and parallel circuits in this podcast
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Series circuits
The current flowing in a series circuit is the same everywhere.
The The potential difference (or voltage) of a supply is a measure of the energy given to the charge carriers in a circuit. Units = volts (V). This is the voltage between two points that makes an electric current flow between them. across a Parts of an electrical circuit, eg resistors, lamps, motors etc. in a series circuit depends on its resistance. Energy is conserved in circuits, so the total potential difference for a series circuit is:
- the sum of the potential differences across the individual components
- the same as the potential difference of the cell
Parallel circuits
Parallel circuits have more than one loop.
An Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons. will not pass through every component on its way round the circuit. The diagram shows a circuit with two bulbs in parallel.
If one of the bulbs is broken, the current can still flow round the circuit through the other loop, so the other bulb stays on.
The lights in a house are wired this way. If one light breaks, the others continue to work. If the lights were wired in series instead, all the lights would go out if one breaks. In a parallel circuit, measurements of the current at different points in the circuit should add up to the ammeter reading close to the cell.
In the circuit above:
- (current at I1) = (current at I3)
- (current at I2) + (current at I4) = (current at I1 or I3)
Since The capacity for doing work. has to be conserved, the energy transferred around the circuit by the electrons is the same whichever path the electrons follow. This means that the potential difference across the components in a parallel circuit is always the same value.