We explain the difference between EMF and voltage with table. The difference between EMF and voltage is in terms of their definitions. The first is a measurement of voltage that occurs within an electrical source. It is the energy provided by a cell per unit of Coulomb charge that passes through the cell. Voltage, on the other hand, is the difference in potential energy between two points in a circuit.
EMF equals the potential difference between the two poles when no current flows through the circuit. Voltage refers to the energy required to transfer an electrical charge from one end of the circuit to the other divided by the magnitude of the charge. Therefore, although EMF and voltage are intrinsically linked, they are also significantly different.
Comparison table between EMF and voltage
| Comparison parameters | EMF | voltage |
| Definition | Defined as voltage produced within an electrical source. | Defined as the potential difference between two given points in a circuit. |
| Formula | Ε = I (R + r) | V = I + R |
| Intensity | Constant intensity maintained | The intensity is not constant |
| Measuring instrument | Measured with an EMF meter. | Measured with a voltmeter. |
| Force operation | Coulomb force operation. | Force operation without Coulomb. |
| Sources | Dynamo, electrochemical cells, solar cells. | Electric and magnetic fields. |
What is EMF?
EMF is short for electromotive force which is defined as the voltage produced within an electrical cell. Energy is converted from one form to another in a generator or battery. For this purpose, one terminal of the generator or battery is positively charged and the other is negatively charged.
Work done per unit charge is indicated by EMF. EMF is the energy provided by a cell or battery per unit of charge coulomb through it. When no current flows through the circuit, EMF equals the potential difference between the two terminals. Volt is the unit of measurement for EMF. The symbol for EMF is ε.
There are several alternative formulas for calculating EMF.
- ε = V + Ir
- V is used to connote the cell voltage
- It is used to connote the current flowing through the circuit.
- r is used to connote the internal resistance of the cell
- and, ε is used to connote EMF
Another formula used to find electromagnetic fields is:
- ε = E / Q where,
- ε means EMF
- E means energy in joules
- Q means charge in coulomb
The formula can be modified taking into account the internal resistance of the cell. Then we get another method to calculate EMF:
- Ε = i (R + r)
- ε means EMF
- It means the current that flows through the circuit.
- R means the resistance offered by the circuit
- R means the internal resistance of the cell.
What is voltage?
Voltage is defined as the amount of potential energy that flows between two points in a circuit. It is also defined as the amount of potential energy available per unit charge.
Voltage can also be defined as the pressure required to push the electrical charge per unit through a conductive loop in a circuit. It is the work done to move a unit charge from one point in the circuit to another.
The unit of measurement for voltage is the same as EMF. Named after the Italian scientist Alessandro Volta, this unit of measurement is shared by EMF and voltage. Volta is credited with discovering the first electronic drums.
Therefore, the voltage is indicated in the equations as ‘V’. Voltage is a product of electric and magnetic fields. Ohm’s law is used to calculate the voltage drop for each resistor. Common voltage symbols include V, ∆V, U, ∆U.
The formula to calculate the voltage:
V = I + R where,
- V connotes voltage
- It connotes the current that flows through the circuit.
- R connotes resistance
Main differences between EMF and voltage
- The main difference between EMF and voltage is that the former represents the voltage within each electrical source, while the latter represents the potential difference between two given points.
- The intensity of the electromagnetic fields is constantly maintained. The intensity of voltage loads can fluctuate. Therefore, the voltage does not have a constant intensity.
- The third difference between the two can be denoted in terms of the measuring instrument used for each. EMF is measured with an EMF meter, while voltage is measured with a voltmeter.
- The sources of each also offer another point of difference. EMF sources include dynamos, electromagnetic cells, solar cells, etc. The voltage is produced by electric and magnetic fields.
- Another notable difference between EMF and voltage is in terms of force operation. EMF is a Coulomb force operation, while voltage is a non-Coulomb force operation.
- While EMF can be measured between the two terminals when no current is flowing through the cell, voltage can be measured between two given points. This is a noticeable difference between EMF and voltage.
- Another interesting point of difference is their cause-effect relationship. EMF is the cause of voltage and voltage is a by-product of EMF.
Final Thought
There are several prominent differences between electromagnetic fields and voltage that powerfully distinguish one concept from another. They are differentiated by their formulas, intensity, measuring devices, force operation and sources.
While EMF denotes the measure of the potential difference between the two terminals of a cell when no current flows through it. Voltage is the measure of the potential difference between two given points when current flows through the cell. The first maintains a constant intensity while the second can fluctuate.
Solar cells, electric generators, and electrochemical cells are sources of EMF, while voltage is produced by an electric or magnetic field. Although both concepts are closely related to electrical circuits and current flow, they are significantly different.
