Resistance in series and parallel circuits

Resistors in series

In a series circuit, the total resistance across all of the components (the 'net resistance') increases as more components are added.

This circuit shows an example of resistors in series.

The two resistors have the same current through them. The potential difference across them will be different if they have different resistances. The total resistance ( R_{T}) for this circuit is R_{1} + R_{2}.

R_{T} = R_{1} + R_{2}

Example: A 2 Ω resistor is placed in series with a 6 Ω resistor. What is the total resistance?

Answer: R_{T} = 2~\Omega + 6~\Omega

R_{T} = 8~\Omega

Resistors in parallel

In a parallel circuit, the net resistance decreases as more components are added, because there are more paths for the current to pass through.

This circuit shows an example of resistors in parallel.

The two resistors have the same potential difference across them. The current through them will be different if they have different resistances.

The total current in the circuit is the sum of the currents through each branch.

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