Electromotive Force Calculator
Calculate EMF for batteries, generators, and circuits with our free online tool
EMF Calculator
About Electromotive Force (EMF)
Electromotive force (EMF) is the electrical action produced by a non-electrical source, such as a battery (converting chemical energy) or generator (converting mechanical energy). It’s measured in volts and represents the energy per unit charge that’s converted from chemical, mechanical, or other forms of energy into electrical energy.
Key Concepts
- EMF vs Voltage: While both are measured in volts, EMF specifically refers to the energy supplied per coulomb of charge, while voltage is the potential difference between two points.
- Internal Resistance: All real voltage sources have some internal resistance that causes the terminal voltage to be less than the EMF when current flows.
- Faraday’s Law: Describes how a changing magnetic field can induce an EMF in a conductor.
- Motional EMF: Generated when a conductor moves through a magnetic field.
How to Use This Calculator
- Select the type of EMF calculation you need (Battery, Faraday’s Law, or Motional EMF)
- Enter the required values in the input fields
- Click “Calculate EMF” to get your result
- The formula used for your calculation will be displayed below the result
Frequently Asked Questions
EMF is the maximum potential difference when no current flows, while terminal voltage is the actual voltage measured when current is flowing. Terminal voltage equals EMF minus the voltage drop across internal resistance (V = EMF – Ir).
Faraday’s law states that the induced EMF in a closed circuit equals the negative of the time rate of change of the magnetic flux through the circuit. The formula is EMF = -N(ΔΦ/Δt), where N is number of turns, ΔΦ is change in flux, and Δt is change in time.
Motional EMF is generated when a conductor moves through a magnetic field, causing the magnetic force to push the free electrons in the conductor to one end. The formula is EMF = BLv, where B is magnetic field strength, L is conductor length, and v is velocity perpendicular to the field.
Yes, EMF can be negative in the context of Faraday’s law, indicating that the induced current flows in a direction that opposes the change in magnetic flux that produced it (Lenz’s Law).