# Difference Between EMF and Voltage

Last Updated on February 9, 2024 by Electricalampere

The primary difference between EMF and voltage is that EMF denotes the voltage present at the terminals of a source in the absence of current flow. In contrast, voltage refers to the voltage at the source’s end when current circulates through the circuit.

## What is EMF?

EMF, or electromotive force, occurs when electrons are separated from atoms by consuming energy in the form of chemical, mechanical, or light. This results in electrically charged particles being formed. EMF can be generated by an electrochemical cell or by changing the magnetic field. The unit of measurement for EMF is volts, and the symbol E denotes it.

The voltage at the ends of the power source when a power source does not supply the current to load equals the EMF, as shown in the below circuit.

## What is Voltage?

Voltage refers to the variation in electrical states on the poles. Electrons move from the negative to the closed electrical circuit’s positive end. Electrical voltage is the amount of work the electric force does in moving the charge from one point to another within the field. The S.I. unit of voltage is volt, which is denoted by V.

The voltage at the ends of the power source when the power source supplies the current to load equals the voltage, as shown in the below circuit.

### Formula for Voltage

The formula for voltage can be expressed in terms of work done and charge.

## Difference Between EMF and Voltage

### Sample Problems

Problem 1: A circuit has a 4,2 V potential differential and a current of 0.6 A. The internal resistance of the battery is 0.3 ohms. Find EMF.

Given Data-
V=4.2V
I= 0.6 A
r=0.3 Ohms

Solution:

Problem 2: The battery has a terminal voltage of 4 volts and an internal resistance of 0.01 ohms. Calculate the amount of current that is being supplied to a load with a resistance of 1 ohm.

Given Data-
V= 4 Volts
r=0.01 Ohms
R= 1 Ohm

Solution:

## Conclusion:

In conclusion, understanding the difference between EMF and voltage is crucial for anyone to comprehend electrical systems and circuits. While both terms are often used interchangeably, they represent distinct concepts in the electrical circuit.