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Physics 8463 - 4.2 Electricity

4.2.2 Series and parallel circuits

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There are two ways of joining electrical components, in series and in parallel.

Some circuits include both series and parallel parts.

 

For components connected in series you need to know that:

there is the same current through each component

the total potential difference of the power supply is shared between the components

the total resistance of components is the sum of the resistance of each component.

Rtotal = R1 + R2

 

where R = resistance, in ohms, Ω

 

 Students are not required to calculate the total resistance of more that two resistors joined in series.

For components connected in parallel you need to know that:

the potential difference across each component is the same.

the total current through the whole circuit is the sum of the currents through the separate components.

the total resistance of two resistors is less than the resistance of the smallest individual resistor.

Students are not required to calculate the total resistance of two resistors joined in parallel.

But for those of you interested in it - click here

Students should be able to:

use circuit diagrams to construct and check series and parallel circuits that include a variety of common circuit components

describe the difference between series and parallel circuits

explain qualitatively why adding resistors in series increases the total resistance whilst adding resistors in parallel decreases the total resistance

explain the design and use of dc series circuits for measurement and testing purposes

calculate the currents, potential differences and resistances in dc series circuits

solve problems for circuits which include resistors in series using the concept of equivalent resistance.