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Home > News & Articles > EMF: Formula, Definition, Examples, Unit, Nature, Importance, EMF vs Potential Difference, and Sample Questions
Updated on 03rd July, 2023 , 5 min read
The electric potential created by an electrochemical cell or by modifying the magnetic field is known as electromotive force, or EMF. The electromotive force (EMF) formula may be written as e = IR + Ir or e = V + Ir, where e is the electromotive force (in volts), I is the current (in amps), R is the load resistance, and r is the internal resistance of the cell, measured in ohms.
The electric force created when any kind of energy is converted into electric energy is known as the electromotive force, or EMF. The EMF is a quantity that is mentioned in the explanations of electromagnetic induction and the behavior of electrochemical cells. The EMF, for instance, quantifies the energy that the generator—the source of the electromotive force—provides to the unit load to move from one position to another in a basic electrical circuit made up of conducting wires, resistors, and wires. This definition of electromotive force refers to the electric potential created by an electromotive force source.
Examples of emf sources include a cell, solar cell, battery, generator, thermocouple, dynamo, etc.
The volt (V) serves as the EMF unit in the International System (SI) since it measures electric potential. In this sense, the electromotive force is defined as the ratio of the energy in Joules (J) produced by an EMF source to the quantity of electric charge that is transported from one location to another during a specific period of time in Coulombs (C). A measurement of 1 V is therefore equal to 1 joule per coulomb.
The electromotive force may be estimated by dividing the effort needed to move an electric charge from one potential to another by the modulus of the electric charge. The EMF formula is as follows-
Where,
E= emf or voltage (V)
W = Energy (Joules)
Q = the electric charge (coulombs).
Electromotive force (emf) and potential difference (PD) are both measured in volts (V).
The Ohm's law formula can also be used. According to Ohm's law, the voltage across two places is precisely proportional to the current flowing through a conductor between them. Note that emf and potential differences are both expressed in volts (V).
The equation for electromotive force is as follows-
Where,
e is the electromotive force (Volts),
I = current (A),
R = Load resistance,
r is the internal resistance of a cell. The SI unit of internal resistance is Ohm (Ω).
For the electromotive force to operate, a number of conditions must be met. It's crucial that there be a potential difference between the two poles. One pole has to be negatively charged, while the other needs to be positively charged. They are required to bear the electrical expenses. A closed or open circuit may be used for this. Which is better is determined by the functioning mechanism or the characteristics of the open and closed circuits.
For Example- In charge of producing an electrical current in an open circuit. The circuit performs poorly when this current flow is disrupted. The link is shown to be ineffective since no correct energy flow is created.
The circuit functions more effectively when it is closed. This is due to the electric current's mobility, which easily leaves the source and generates energy. Batteries and generators are good examples of this. A conducting wire and a bulb are connected to a battery. The generator is turned on when the current has reached it and passed through the switch. Generators are well recognized for converting mechanical energy and serving as excellent EMF sources. Consequently, a closed electrical circuit is considerably more likely to be successful than an open one.
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EMF is the quantity of energy (in any form) converted into electrical energy per coulomb of charge, whereas the potential difference is the quantity of electrical energy converted into other kinds of energy per coulomb of charge.
Solution: The electrical potential difference between two places has been defined as a term. Or, to put it another way, we may say it counts the amount of energy that is moved between the two places in an electrical circuit.
Solution: We need emf because it may be used to gauge how much current is flowing through an electrical circuit. While the other terminal is negatively charged, one is positively charged. The letter represents EMF.
Solution: In the absence of current flowing through the electrical circuit, the amplitude of the emf is equal to the potential difference detected across the cell terminal. Faraday's law of induction is used to discover this. The size of the electromagnetic field (EMF) that is present in the circuit is equal to the absolute value of the temporal rate of change of the magnetic flux flowing through the circuit. The emf present in the circuit in this instance is always equal to 1.
Solution: Electromagnetic force, or emf, and voltage are closely related. It is electrical force or energy that comes from a non-electrical source, such as a battery. The electromotive force is believed to be created when variations in the magnetic field take place on a surface. The potential difference measured across the cell's terminals when no current is flowing through the circuit has been used to quantify the magnitude of the emf. Volts, or joules per coulomb, are the SI unit for emf.
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By - Nikita Parmar 2023-08-25 09:48:44 , 11 min readAns. The electromotive force may be estimated by dividing the effort needed to move an electric charge from one potential to another by the modulus of the electric charge. The EMF formula is E = W/Q.
Ans. Contrary to what its name suggests, electromotive force is the amount of energy needed to move an electric charge from its lowest to its maximum potential. As a result, although it is called a force, it really measures an electric potential.
Ans. Emf is significant since it aids in determining the quantity and strength of energy. This energy is concerned with the circuit’s internal current flow. It may also be described as the differential in potential between the two locations of the cell terminal.
Ans. The volt (V), sometimes known as the potential difference (U), is the unit of electromotive force (EMF). One coulomb of electrical charge is equal to one joule of energy expenditure, or one volt.
Ans. EMF is an abbreviation for electromotive force. The conversion of any kind of energy into electrical energy, which creates an electric current, is represented by this number.
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