What is electromotive force? What's its relationship to Voltage?

In summary, electromotive force (EMF) refers to the energy provided per unit charge by a source, such as a battery or generator, to drive electric current through a circuit. It is measured in volts and represents the potential difference when no current flows. Voltage, on the other hand, is the potential difference across a circuit element when current is flowing. While EMF can be considered the source of voltage in a circuit, actual voltage can be affected by factors such as internal resistance and load conditions.
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StoicIndieHacker369
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New poster has been reminded to post their whole question at PF and not just link to external websites.
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This was a question that I posted on the Physics stack exchange, but I'm posting it here to have a higher probability of receiving an adequate answer.
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It is fine to post the question on both sites, but not this way. The question should be self contained on each site so that people can understand what you are asking on each site directly.
 
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I will answer your question but only the one here on PF.

Electromotive force is basically the potential difference between two points before they are connected .

Now there are two cases after connection is made between the points of 2 different potentials

Case 1: EMF = Voltage
This happens when there is no resistance and no loss of energy (only possible in ideal circuits) and there is no internal resistance in the voltage source

Case 2: EMF > Voltage
This happens in practical circuits we see in daily life . Here the components have resistances , charges leak , voltage source has internal resistance and energy is lost as heat/light .

Voltage can never be greater than EMF as EMF is a perfect tendency or a perfect potential difference(EMF is in a open circuit ) but voltage is the the result of applying EMF in a closed circuit
 
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In circuit analysis, voltage at a the output terminals of a power source that is open circuit is taken as the same thing as the EMF inside the power source. This is case 1 above.

When the power source is connected to something with finite resistance the voltage drops according to both (1) the amount of internal resistance in the power source prior to the output terminals, and (2) the amount of current drawn by the load. This is case 2 above. Zero internal resistance, or infinite external load, would mean that the terminal voltage is the same as the EMF, just as in case 1 above.
 
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FAQ: What is electromotive force? What's its relationship to Voltage?

What is electromotive force (EMF)?

Electromotive force (EMF) is a measure of the energy provided by a source per unit charge as it moves through an electrical circuit. It is not a force in the traditional sense but rather a potential difference that drives electric current. EMF is typically produced by sources such as batteries, generators, and solar cells.

How is electromotive force different from voltage?

While both electromotive force (EMF) and voltage refer to electrical potential, they are used in different contexts. EMF refers specifically to the potential difference created by a source when no current is flowing, whereas voltage can refer to the potential difference across any two points in a circuit, which may include the effects of resistance and current flow.

What units are used to measure electromotive force?

Electromotive force is measured in volts (V), which is the same unit used for voltage. One volt is defined as the potential difference that will move one coulomb of charge through one joule of energy.

Can electromotive force exist without current flow?

Yes, electromotive force can exist without current flow. EMF is defined when there is no load connected to the source, meaning that it represents the potential difference available to drive current when a circuit is completed. Once the circuit is closed and current begins to flow, the voltage across components may differ due to resistance.

What factors affect electromotive force in a circuit?

Several factors can affect the electromotive force in a circuit, including the type and configuration of the power source (such as its chemistry in batteries), the temperature, and the load connected to the circuit. In generators, the speed of rotation and the strength of the magnetic field also play significant roles in determining EMF.

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