# Induced EMF

by Soaring Crane
Tags: induced
 P: 483 If a switch of a circuit system of a wire loop is open, then no current flows. There would also be no magnetic flux and induced current if it remains open, right? What is the difference between current and induced current? I know the latter arises from a change in the magnetic field, but what else is there to know? Thanks.
P: 4,003
 Quote by Soaring Crane What is the difference between current and induced current? I know the latter arises from a change in the magnetic field, but what else is there to know? Thanks.
An induced current has a direction such that the magnetic field due to the induced current opposes the change in the magnetic field that induces the current

marlon
 P: 4,003 Besides, if there is no current in the primary chain (coming from a battery) there will still be an induced current in the secondary chain (no battery connected to it) because the magnetic field will 'break down' and thus it will induce a current in the second chain. the two chains are mostly interconnected by some ferromagnetic material marlon
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## Induced EMF

The difference of both names & concepts stands in the cause that produces the curerents."The latter" appears from a change in the magnetic flux (which is a scalar,BTW,so we worry only with changes in time,and not in space)...I believe that's what the theorem/law of Faraday says...

So to use equations,the difference could be visualized from

$$\vec{E}=-\nabla\phi$$

and

$$\mbox{induced \ electromotive \ tension} =-\frac{d}{dt}\iint_{S} \vec{B}\cdot \vec{n} \ dS$$

Daniel.
 P: 4,003 Perhaps the most striking difference is the fact that electric potential has meaning only for E-fields that are produced by static charges (like the E-field between two electrodes); it has NO meaning for E-fields that are produced by induction... to dextercioby : talking about blabla-tension and multi-dimensional integrals ain't gonna do much good in the grade K-12-level, amigo marlon
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 Quote by marlon to dextercioby : talking about blabla-tension and multi-dimensional integrals ain't gonna do much good in the grade K-12-level, amigo marlon
1.I didn't realize the thread was in K-12.
2.In HS,everyone knows what an electromotive tension is...

Daniel.

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