3. Series and Parallel Circuits

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3. Series and parallel circuits serve different purposes in households

3.1 - Identify the difference between series and parallel circuits

A series circuit is an electric circuit that allows for only one pathway for the flow of electric current

A parallel circuit is a circuit that has more than one pathway for the flow of electric current

3.2 - Compare parallel and series circuits in terms of voltage across components and current through them

Series circuits allow electric current to flow only in one pathway - only one way the electricity can travel from the positive terminal to the negative terminal

The voltage is split across each component in the circuit according to the component's resistance

The current at any point along the circuit is equal across all components

If a component of the circuit fails, the whole circuit fails as there is only one pathway for the current to flow along the circuit

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Parallel circuits allow electric current to flow in more than one pathway

The voltage is the same among all circuit components that are connected in parallel

The current is split among the parallel circuit components

If a component of the circuit fails, only the components within its pathway will be affected, and the other pathways will not be affected as the current can still pass through them

3.3 - Identify the use of ammeters and voltmeters

3.4 - Explain why ammeters and voltmeters are connected differently in a circuit

An ammeter is a device used to measure the size of an electric current

An ideal ammeter will have a very small resistance in order to not reduce the current flowing through the circuit

Since current along any part of a series circuit is equal, an ammeter needs to be placed in series with the circuit or the resistor that is to have its current measured

A voltmeter is a device used to measure the voltage across a component f an electric circuit

An ideal voltmeter should be able to voltage without interfering with the circuit - this is achieved by having a voltmeter with a very large/infinite resistance, so little current is diverted to the voltmeter

Since all circuit components connected in parallel will have the same voltage, a voltmeter should be placed in parallel to the component that is to have its voltage measured

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Often there are more complex circuits made up of combinations of series and parallel circuits

In order to make calculations, these need to be broken down into individual series and parallel circuits,, making use of the characteristics of each type of circuit for each calculation

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3.5 - Explain why there are different circuits for lighting, heating and other appliances in a house

Most household circuits employ a combination of series and parallel circuits

Usually there are three types of circuits, one for lighting, one for heating, and one for power points

These are connected in parallel each other, and are supplied by an AC voltage of 240V, the standard voltage in homes

This parallel design is important because:

Each of the circuits draws a different amount of current from the main power supply, only a parallel circuit allows this

It allows the fuse capacity (circuit breaker) to be tailored individually for each circuit

If one circuit breaks down, the others will still continue to function, as it is on a separate branch of the whole circuit

Within each of the main circuits, devices may be connected in series or parallel to each other depending on the design and uses of each supply

Series connections are generally simpler, however if one component fails, all the others along the same series will also fail

Voltage drop will also have to be accounted for if components are connected in series