What is EMF?

Member • Mar 9, 2009

The electromagnetic field is a physical <a href="https://en.wikipedia.org/wiki/Field_%28physics%29" target="_blank" rel="nofollow noopener noreferrer">Field %28Physics%29</a> produced by <a href="https://en.wikipedia.org/wiki/Electric_charge" target="_blank" rel="nofollow noopener noreferrer">Electric Charge</a>. It affects the behavior of charged objects in the vicinity of the field.
The electromagnetic field extends indefinitely throughout space and describes the <a href="https://en.wikipedia.org/wiki/Electromagnetism" target="_blank" rel="nofollow noopener noreferrer">Electromagnetism</a>. It is one of the four <a href="https://en.wikipedia.org/wiki/Fundamental_force" target="_blank" rel="nofollow noopener noreferrer">Fundamental Force</a> of nature (the others are <a href="https://en.wikipedia.org/wiki/Gravitation" target="_blank" rel="nofollow noopener noreferrer">Gravitation</a>, the <a href="https://en.wikipedia.org/wiki/Weak_interaction" target="_blank" rel="nofollow noopener noreferrer">Weak Interaction</a>, and the <a href="https://en.wikipedia.org/wiki/Strong_interaction" target="_blank" rel="nofollow noopener noreferrer">Strong Interaction</a>). The field propagates by <a href="https://en.wikipedia.org/wiki/Electromagnetic_radiation" target="_blank" rel="nofollow noopener noreferrer">Electromagnetic Radiation</a>; in order of increasing energy (decreasing <a href="https://en.wikipedia.org/wiki/Wavelength" target="_blank" rel="nofollow noopener noreferrer">Wavelength</a>) electromagnetic radiation comprises: <a href="https://en.wikipedia.org/wiki/Radio_wave" target="_blank" rel="nofollow noopener noreferrer">Radio Wave</a>, <a href="https://en.wikipedia.org/wiki/Microwave" target="_blank" rel="nofollow noopener noreferrer">Microwave</a>, <a href="https://en.wikipedia.org/wiki/Infrared" target="_blank" rel="nofollow noopener noreferrer">Infrared</a>, <a href="https://en.wikipedia.org/wiki/Visible_spectrum" target="_blank" rel="nofollow noopener noreferrer">Visible Spectrum</a>, <a href="https://en.wikipedia.org/wiki/Ultraviolet" target="_blank" rel="nofollow noopener noreferrer">Ultraviolet</a>, <a href="https://en.wikipedia.org/wiki/X-ray" target="_blank" rel="nofollow noopener noreferrer">X Ray</a>, and <a href="https://en.wikipedia.org/wiki/Gamma_ray" target="_blank" rel="nofollow noopener noreferrer">Gamma Ray</a>.
The field can be viewed as the combination of an <a href="https://en.wikipedia.org/wiki/Electric_field" target="_blank" rel="nofollow noopener noreferrer">Electric Field</a> and a <a href="https://en.wikipedia.org/wiki/Magnetic_field" target="_blank" rel="nofollow noopener noreferrer">Magnetic Field</a>. The electric field is produced by stationary charges, and the magnetic field by moving charges (currents); these two are often described as the sources of the field. The way in which charges and currents interact with the electromagnetic field is described by <a href="https://en.wikipedia.org/wiki/Maxwell%27s_equations" target="_blank" rel="nofollow noopener noreferrer">Maxwell%27S Equations</a> and the <a href="https://en.wikipedia.org/wiki/Lorentz_force_law" target="_blank" rel="nofollow noopener noreferrer">Lorentz Force Law</a>.

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just2rock

Member • Mar 9, 2009

true...with emf we can measure voltage deflections too

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shoaib_y4u2

Member • Mar 11, 2009

guys we relate EMF with voltage y is dat so.... EMF is field ryt?

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raj87verma88

Member • Mar 11, 2009

Electro-Motive Force can be used to determine voltage direction.
Electro-Magnetic Field ........ Syedaafaq has explained it.

They are two different things. The starter of this thread got confused and he/she mixed the two names.

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morganparkar

Member • Mar 11, 2009

praba230890
What is electromagnetic force(emf).please give me a brief explanation about it

Hi Friend,

Electronic Music Foundation (EMF) is an ensemble of programs that provide different perspectives on how music, sound art, technology, and science come together to enhance human creativity and communication. The programs relate to public events, dissemination of information, and access to materials. The following paragraphs list and describe the programs.

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raj87verma88

Member • Mar 12, 2009

morganparkar
Hi Friend,

Electronic Music Foundation (EMF) is an ensemble of programs that provide different perspectives on how music, sound art, technology, and science come together to enhance human creativity and communication. The programs relate to public events, dissemination of information, and access to materials. The following paragraphs list and describe the programs.

I don't think this is what the Thread Starter wanted as an answer. He has specified "Electro Magnetic Force". Please read first before answering.

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Ernesha

Member • Mar 15, 2009

An infinite-range attractive or repulsive force which acts between charged particles. A particle at rest feels only the force due to the electric field , called couloumbs law.

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Ernesha

Member • Mar 15, 2009

In physics, the electromagnetic force is the force that the <a href="https://en.wikipedia.org/wiki/Electromagnetic_field" target="_blank" rel="nofollow noopener noreferrer">Electromagnetic Field</a>electromagnetic field exerts on electrically charged particles. It is the electromagnetic force that holds electrons and protons together in <a href="https://en.wikipedia.org/wiki/Atom" target="_blank" rel="nofollow noopener noreferrer">Atom</a>atoms, and which hold atoms together to make molecules. The electromagnetic force operates via the exchange of <a href="https://en.wikipedia.org/wiki/Messenger_particle" target="_blank" rel="nofollow noopener noreferrer">Messenger Particle</a>messenger particles called photons and <a href="https://en.wikipedia.org/wiki/Virtual_photons" target="_blank" rel="nofollow noopener noreferrer">Virtual Photons</a>virtual photons. The exchange of messenger particles between bodies acts to create the perceptual force whereby instead of just pushing or pulling particles apart, the exchange changes the character of the particles that swap them.
:roll: 😛

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just2rock

Member • Mar 15, 2009

shoaib_y4u2
guys we relate EMF with voltage y is dat so.... EMF is field ryt?

A si already discussed EMF can be used to variate voltage deflection since its Motive force,another is their as Raj mentioned

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Ernesha

Member • Mar 16, 2009

According to Maxwell, even a potential difference can have the same effect as an emf. Nevertheless, normal usage does not consider a voltage difference as a source of emf.

For a resistor the voltage difference across its ends serves as the sole source of emf.
For a voltaic cell the net emf is the sum of the chemical emf, which always tends to drive current so as to discharge the cell, and the voltage difference emf across its terminals. The combination of the two emfs can drive current in either direction, thus permitting both charge and discharge; in equilibrium, where there is zero current, these two emfs cancel.
For a circuit as a whole, such as one containing a resistor in series with a voltaic cell, voltage does not contribute to the overall emf, because the voltage difference on going around a circuit is zero. (See <a href="https://en.wikipedia.org/wiki/Kirchhoff%27s_circuit_laws" target="_blank" rel="nofollow noopener noreferrer">Kirchhoff%27S Circuit Laws</a>)
For a circuit consisting of a capacitor that discharges through a resistor, the emf that drives current is solely due to the voltage difference across the resistor, and due to the capacitor.

If a source of emf is not connected to an external resistor, then an electric current cannot flow through that resistor (Ohm's Law). In this case, between the terminals of the source there must exist a true electric field that produces a voltage difference that exactly cancels the emf of the source.
The source of this true electric field is the electric charge that has been separated by the mechanism generating the emf <a href="https://en.wikipedia.org/wiki/Electromotive_force#cite_note-5" target="_blank" rel="nofollow noopener noreferrer">Electromotive Force Cite Note 5</a>. For example, the chemical reaction in a voltaic cell stops when the electric field across each electrode is strong enough to stop the reactions at each electrode.
This electric field between the terminals of the battery creates an electric <a href="https://en.wikipedia.org/wiki/Potential_difference" target="_blank" rel="nofollow noopener noreferrer">Potential Difference</a> that can be measured with a <a href="https://en.wikipedia.org/wiki/Voltmeter" target="_blank" rel="nofollow noopener noreferrer">Voltmeter</a>. The polarity of this measured potential difference is always opposite to that of the generated emf. The value of the emf for the battery (or other source) is the value of this 'open circuit' voltage. When the battery is charging or discharging, the emf [IMG]

itself cannot be measured directly. It can, however, be inferred from a measurement of the current I and voltage difference V, provided that the internal resistance has already been measured: I=( [IMG]

-V)/r.
One of Volta's great contributions to science was to recognize that a voltaic cell has two sources of emf, the chemical reactions at each electrode. He showed that they provide distinct emfs [IMG]

and

that oppose one another, so that two identical electrodes give no net emf, but that two different electrodes give a net emf of [IMG]

, which we assume is positive. A schematic of this circuit would have a long electrode 1 and a short electrode 2, to indicate that electrode 1 dominates. Volta's law about opposing electrode emfs means that, given ten electrodes (e.g. zinc and nine other materials), which can be used to produce 45 types of voltaic cells (10*9/2), only nine relative measurements (e.g. copper and each of the nine others) are needed to get all 45 possible emfs that these ten electrodes can produce.

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Ernesha

Member • Mar 16, 2009

this illustrates why EmF and VOLTAGE are interconnected

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