Ohm’s Law in Series Circuits

As we all know that a series circuit has two or more than two series resistors. We can apply Ohm’s law in series circuits by solving the series resistors first and then by applying the formulas for series circuits.

Resistors in series

Two or more resistors are simply added in series to obtain the equivalent resistance.

The general formula is:

Req = R1 + R+ R3+ … + Rn

For two resistors:

Req = R1 + R2

In such case, the resistor R in formulas of Ohm’s law will be replaced by Req.

Let’s do a simple example for learning it:

A 12-volt battery power two series resistors of 5-ohm and 30-ohm. Find the current flowing through the series circuit.


So a current of 0.342 A will flow through it.