Difference between EMF and Potential Difference

Introduction

EMF and Potential Difference are one of the major terms used in the electric circuits and widely used to know the voltages of the current passing in the circuit or a cell. So, in this article, we are going to learn about the EMF and Potential difference in the electrical circuit. We also going to learn how it is calculated and what are the factors that are bringing difference in between the EMF and Potential difference. We are also going to know how and when the EMF and the potential difference are used in the circuit.

EMF

EMF can be defined as the potential difference between the two end terminals of a negative and positive terminal of a cell or a battery when the electric circuit is open. It can also be defined as the potential difference between the two terminals of the battery when no current is passing in the cell or the electric circuit in which the cell is connected. There will be no effect of the resistance that is present in the circuit over the value of EMF. The EMF can also be called as Electromotive force. With the help of the EMF value, we can calculate the voltage of a cell without considering the resistance present in the electrical circuit when the current flow is zero or electric circuit is open. An EMF meter can be used to measure the EMF in the open circuit. Voltmeter can also be used in measuring the EMF of the cell present in the electric circuit.

Potential Difference

Potential difference can be defined as the voltage difference that is calculated between any two points of the electric circuit when the current is flowing through the circuit, or the electric circuit is closed. The potential difference can also be defined as the voltage difference between the terminals of the cell present in closed electric circuits. The potential difference can be calculated using the voltmeter that is connected between the two points of an electric circuit. The resistance is considered in calculating the potential difference of the circuit. The resistance will be removed from the potential difference calculated between the points to get the exact voltage in between the points.

Formulas

EMF

The EMF of a cell is calculated using the two different formulas or equations in which the energy and charge are used to calculate the EMF of the energy source of the electric circuit.

ε=E/Q

In this equation, the EMF is calculated by dividing the energy that is already present in the circuit by the Charge that is present in the circuit.

In other case, the EMF is calculated using the OHM’s law

ε=I(R+r)

Where,

I = current in the cell
R = Resistance present in the circuit
r = Internal resistance present in the cell connected to the circuit
V = voltage

Potential difference

Potential difference can be calculated in different ways. The formula for calculating the potential difference of the circuit between two points is

V = W / q

Where,

V = voltage difference between the two points of the electric circuit
W = Work done moving in the unit charge
q = Unit electric charge