## EMF Formula

EMF is defined as electromotive force, which determines the potential difference across the battery’s terminals when the flow of current is zero. The readings may not be mentioned before because they would contrast, but every battery has internal resistance. It’s the same as the normal resistance that decreases. The difference is an exceeding circuit, but it exists in itself.

## About the Topic

The EMF or emf is the energy delivered by an electric battery or a cell per coulomb of charge passing through it. The magnitude of emf is adequate for potential difference across the cell terminals when there’s no current flowing through the circuit. A device for measuring an electromotive force by balancing it against the potential difference created by enacting a known current through a comprehended variable resistance.

## Formula

e = E/Q = I(R+r)

E = emf or voltage (V), W = Energy (Joules), and Q denote charge (Coulombs). Both emf (electromotive force) and PD (potential difference) are measured in V (Volts).

e is that the electrical phenomenon (Volts),

I = current (A),

e = E/Q

R = Load resistance,

Q = Coulomb

r is that the internal resistance of the cell is estimated in ohms.

## Solved Examples

**1. Find out the electromotive force of a circuit with energy and charge of 2400 J and 10 C.**

E = 2400, Q = 10

Operating the formula we get,

ε = E/Q

= 2400/10

= 240 V

**2. Find out the charge of a circuit with energy and the terminal voltage of 900 J and 30 V.**

We have,

E = 900

ε = 30

Using the formula we get,

ε = E/Q

=> Q = E/ε

=> Q = 900/30

=> Q = 30 C