Enter the total work done and the total charge into the calculator to determine the electromotive force.

Electromotive Force Formula

The following equation is used to calculate the Electromotive Force.

E = W / Q

  • Where E is the electromotive force (Volts)
  • W is the work done
  • Q is the charge

To calculate an electromotive force, divide the work done by the non-electrical source by the total charge.

What is an Electromotive Force?


The electromotive force or voltage (EMF) is the energy per unit charge. It is also called the potential difference between two points.

Electromotive force is measured in volts (V), and one volt is the potential for producing a current of one ampere with a power consumption of one watt.

The higher the voltage of an electric power source, such as a battery, the greater the amount of electrical energy it can generate for a given amount of time, or the faster it can charge an electrically powered device.

How to Calculate Electromotive Force?

Example Problem:

The following example outlines the steps and information needed to calculate Electromotive Force.

First, determine the work done by the system. In this case, the work done is 40 volts-coulombs.

Next, determine the electrical charge. In this case, the electrical charge is 4 coulombs.

Finally, calculate the electromotive force using the formula above:

E = W / Q

E = 40/ 4

E = 10 volts