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?

Definition:

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

FAQ

What is the difference between electromotive force and voltage?

Electromotive force (EMF) and voltage are often used interchangeably, but they have distinct meanings. EMF refers to the energy supplied per charge to move it from one point to another, often generated by a battery or generator. Voltage, on the other hand, is the potential difference between two points in a circuit. While EMF is the cause, voltage is the effect observed across a load in the circuit.

Can electromotive force be negative?

Yes, electromotive force can be negative. This occurs when the direction of the energy supply is opposite to the direction assumed in the circuit analysis. It’s a way to indicate that the energy source (like a battery) is absorbing energy rather than supplying it, which can happen in scenarios like charging a battery.

How does the electromotive force affect an electric circuit?

The electromotive force (EMF) is crucial for the operation of an electric circuit as it is the source of energy that drives the flow of electrons through the circuit. A higher EMF in a circuit means that more energy is available to move the electrons, potentially resulting in a higher current flow if the resistance of the circuit does not change. Essentially, EMF determines how much electrical energy is supplied to the circuit per unit charge.