Electricity Basics: Understanding Electromotive Force (EMF)

In summary, electromotive force (EMF) is the amount of mechanical energy converted into electrical energy when unit charge passes through a generator. This energy is then used to power external circuits and can be converted into other forms such as heat or light. The EMF is similar to voltage and is affected by the internal resistance of the generator. The open circuit voltage is higher than the effective voltage due to this resistance. EMF is an energy and must be conserved when used to power external circuits.
  • #1
Basel A
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A generator is charcterized by its internal resistance and electromotive force E. What is meant by electromotive force..(please i need perfect answer)
 
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  • #2
The standard definition (for a generator) would be "The electromotive force of a generator (dynamo) is the amount of mechanical energy converted into electrical energy when unit charge passes through it." (Measured in joule per coulomb or volt)
The generator has to do work to move charge through it; in doing so the charges gain electrical energy. When connected to an external circuit, this energy is converted into other forms, for example heat in resistors, when the charges flow around that circuit.
 
  • #3
There is no "perfect" definition.
try wikipedia at http://en.wikipedia.org/wiki/Electromotive_force for a further discussion.
A generator, or alternator, is characterized by a lot more than the two (important) factors you stated.
 
  • #4
as i have learned , electromotive force is the the energy requires to drive +1 charge(unit charge) along the path.. say you have a circuit which describes as a closed path with 'no' any resistance... then you don't have any disturbance to drive any charge along that path..that means the required EMF is zero to drive the charges(current).. and this EMF is very much similar as the voltage(well I don't see a much difference)... and for a generator EMF is the same definition and the internal resistance is the resistance inside that generator(independent of the external circuit).. simply EMF is the voltage of the generator... but there is something to consider when you take the open circuit voltage and the effective voltage... open circuit voltage of a gen is higher than the effective one.. (this difference comes bcoz of the internal resis)...sketch a circuit diagram with internal resis... and don't forget EMF is an energy... again take into consideration , if you use EMF to drive charges that energy EMF converts to the energies like heat(in resistors), maybe light(if there are bulbs in the circuit) etc.. because you use EMF against those disturbances(resistors, motor loads etc) and there is something that should be happened to that used EMF energy...(energy conservation).. hope this would be helpful..
 

FAQ: Electricity Basics: Understanding Electromotive Force (EMF)

1. What is electromotive force (EMF)?

Electromotive force, commonly referred to as EMF, is the force that drives electric current. It is the potential difference between two points in an electrical circuit that causes the flow of electrons from one point to another.

2. How is EMF measured?

EMF is measured in volts (V) using a voltmeter. This device measures the potential difference between two points in an electrical circuit. It is important to note that EMF is not a physical force, but rather a measure of the energy per unit charge.

3. What is the difference between EMF and voltage?

EMF and voltage are often used interchangeably, but they are not exactly the same. EMF is the force that causes the flow of electrons, while voltage is the potential difference between two points in an electrical circuit. In other words, voltage is a measure of EMF.

4. How does EMF affect the flow of electrons?

EMF is directly proportional to the flow of electrons in an electrical circuit. This means that the higher the EMF, the greater the flow of electrons. However, other factors such as resistance and capacitance also play a role in determining the flow of electrons.

5. What are some common sources of EMF?

EMF can be generated by a variety of sources, including batteries, generators, solar panels, and power plants. It is also present in natural phenomena such as lightning. In everyday life, EMF is commonly used to power electronic devices such as smartphones, laptops, and household appliances.

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