Electromotive Force vs. Potential Difference

Attribute	Electromotive Force	Potential Difference
Definition	The energy per unit charge supplied by a source of electrical energy	The energy per unit charge required to move a charge between two points in an electric field
Symbol	EMF or ε	V or ΔV
Unit	Volts (V)	Volts (V)
Direction	Always in the direction of the electric field	Depends on the direction of the charge movement
Source	Generated by a source of electrical energy (e.g., battery)	Exists in any electric circuit due to potential difference between points

Definition

Electromotive force (EMF) and potential difference are two important concepts in the field of electricity. EMF is the energy per unit charge supplied by a source of electrical energy, such as a battery or generator. It is measured in volts and represents the maximum potential difference that can be established by the source. On the other hand, potential difference, also known as voltage, is the difference in electric potential between two points in an electric circuit. It is also measured in volts and represents the amount of work done per unit charge in moving a charge between the two points.

Source of Energy

One key difference between EMF and potential difference is their source of energy. EMF is the energy supplied by the source of electrical energy, while potential difference is the energy used by the charges in the circuit. In other words, EMF is the driving force that pushes the charges through the circuit, while potential difference is the work done by the charges as they move through the circuit.

Direction of Energy Flow

Another difference between EMF and potential difference is the direction of energy flow. EMF is always directed from the positive terminal of the source to the negative terminal, regardless of the direction of current flow in the circuit. On the other hand, potential difference is always directed from the higher potential point to the lower potential point in the circuit, in the direction of current flow.

Measurement

EMF is measured in volts and is represented by the symbol E. It is the maximum potential difference that can be established by the source of electrical energy. Potential difference, on the other hand, is also measured in volts and is represented by the symbol V. It represents the actual potential difference between two points in an electric circuit, which may be less than the EMF due to internal resistance in the circuit.

Internal Resistance

One important factor to consider when comparing EMF and potential difference is internal resistance. EMF is the ideal voltage supplied by the source, assuming no internal resistance in the circuit. However, in real-world circuits, there is always some internal resistance in the source, which causes a drop in potential difference across the circuit. This means that the potential difference measured in the circuit will be less than the EMF of the source.

Effect on Circuit Components

EMF and potential difference have different effects on the components of an electric circuit. EMF is the maximum potential difference that can be established by the source, so it represents the maximum energy available to the circuit. Potential difference, on the other hand, is the actual energy used by the charges in the circuit, so it represents the work done by the charges as they move through the circuit. This difference in energy flow can affect the performance of circuit components, especially in high-resistance circuits.

Applications

EMF and potential difference have different applications in the field of electricity. EMF is used to calculate the maximum potential difference that can be established by a source of electrical energy, such as a battery or generator. Potential difference, on the other hand, is used to measure the actual potential difference between two points in an electric circuit, which may be less than the EMF due to internal resistance. Both concepts are essential for understanding the behavior of electric circuits and designing efficient electrical systems.