# Formula: Equivalent resistance of a series connection of resistors Equivalent resistance    Single resistance

## Equivalent resistance

Unit
The total resistance (equivalent resistance) of a series circuit is the sum of individual resistors. For example, if you have a series circuit with three resistances $$R_1$$, $$R_2$$ and $$R_3$$, then the total resistance $$R$$ is given by: $R ~=~ R_1 ~+~ R_2 ~+~ R_3$

For example, if the first resistance is $$R_1 = 200 \, \Omega$$, the second resistance is $$R_2 = 50 \, \Omega$$, and the third resistance is $$R_3 = 100 \, \Omega$$, then the total resistance of the series circuit is: \begin{align} R &~=~ 200 \, \Omega ~+~ 50 \, \Omega ~+~ 100 \, \Omega \\\\ &~=~ 350 \, \Omega \end{align}

## Single resistance

Unit
One of the resistances of the series circuit.

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