### Voltage Divider Rule

It can be quite useful to determine how a voltage appearing across two series resistors “divides” between them.

Consider the circuit shown below: By Ohm’s Law, the current in the resistors is: By application of Ohm’s Law again, the voltage across R1  is:

v1 = R1 . i

and therefore: Similarly, the voltage across R2  is: These equations describe how the voltage is divided between the resistors. Because of this, a pair of resistors in series is often called a voltage divider.

Example:

We want to find the voltage v in the circuit below: Combining the series connection of the 1 ohm and 3 ohm resistors, we obtain the Now the pair of 4 ohms resistors in parallel can be combined as shown below: By voltage division: Returning to the original circuit and applying voltage division again yields: #### Engineering Tutorial Keywords:

• the formula of current divider when series-parallel circuit
• voltage divider example
• voltage divider rule yields
• voltage divider through a resistor