emf's (1 Viewer)

[Nazalodeon]

Hi guys,
I was reading up on electromagnetic induction and was totally stumped about emf's. I was wondering if someone could explain to me what a emf is, a induced emf how this works. So far, i came up with this definition of a emf, although i think its wrong.

An emf is an electromotive force. When a conductor is connected across a battery to make a circuit, the current that flows through that conductor will flow around that circuit. Eventually, that current will pass back through the battery and gain more energy. The emf is the amount of energy that a single current gain as it passes through that battery once again.

 

[shinji]

EMF : Elecromotive Force.
This is the force that is experienced by a current carrying conductor as it passes through an external magnetic field.

To determine the direction of this force, use the right hand palm rule.

Electromagnetic Induction is the creation of an emf (to induce an emf) in a conductor when it is in relative motion to a manetic field.

Well, that's my view on it. your better off getting asecond opinion on it.

 

[rama_v]

Emf is an unfortunate term as it is not really a force. It refers to a potential difference in volts in a conductor. In modern terms, the emf of a battery is the maximum possible voltage that the battery can provide between its terminals.

When a conductor is moved through a magnetic field (uniform or non-uniform), the conductor experiences a change in magnetic flux. A potential difference is created The strength of the emf induced in that conductor is given by faradays law,

emf = -d(flux)/dt =-d/dt (BACos@)

[The equation is not in the sylabus]. The negative sign arises from Lenz's law. Quick example: If a rod was moved alogn two rails at a constant speed through a uniform magnetic field, and the area is given by l*x, where x is the variable, then
emf = -d/dt(Blx) = -Bl (dx/dt) = -Blv .

As the conductor moves through the magnetic field, a magnetic force acts on electrons in the conductor forcing them to one end. This creates a potential difference in the rod which is maintained so long as the rod is in motion.

 

[Nazalodeon]

So is it simply what Shinji said and is

"This is the force that is experienced by a current carrying conductor as it passes through an external magnetic field"?

 

[STx]

I agree with rama, E.M.F. is the generated potential difference which is equal to the rate of change of magnetic flux in the circuit.

 

[Nazalodeon]

Okay, tell me if i have this wrong...
So, the 'E.M.F' is the rate of change of magnetic flux in the circuit. Which simply is the rate of change of the amount of magnetic field that passes a given area.

OR:

A E.M.F is simply the voltage or potential difference (voltage between two points) which is provided by a power supply.

 

[STx]

correct