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What is the difference between eddy current and induced current? 
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#1
Mar1511, 09:19 AM

P: 97

what is the difference between eddy current and induced current? and how could eddy current cause energy loss? does the induced current cause also energy loss?
what is the difference between back emf and induced emf? all these things are confusing me. thanks in advance 


#2
Mar1511, 10:51 AM

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#3
Mar1511, 11:19 AM

P: 97

who causes the eddy current, self induction or back emf



#4
Mar1511, 02:08 PM

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What is the difference between eddy current and induced current?
The eddy current is caused because the alternating current in the coil creates an electric field within the area enclosed by the coil. This emf is determined by Faraday's law: [tex]emf = \oint E\cdot ds = \frac{d\phi}{dt} = \oint B\cdot dA[/tex] The line integral of the electric field around a closed loop path is equal to () the rate of change of the magnetic flux through the area enclosed by the path. So, for a coil of wire carrying an alternating current there will be an electric field created all along any closed path inside the area enclosed by the coil. The magnitude of the emf created along any path is determined by the time rate of change of the flux through the area enclosed by that path. If there is just air in that enclosed area, there are no eddy currents: the induced emf cannot move the electrons because they are stuck to the atoms in the air. However, if there is an iron core in that space, the electric field causes electrons in the iron core to move (since iron is a conductor, the electrons are free to move). These electron motions are the eddy currents. AM 


#5
Mar1611, 03:49 PM

P: 97

"an electric motor that is already spinning consumes less power than one that is starting or changing direction" my question is why???
isn't the variation of magnetic flux when the motor is already spinning is greater than that when the motor is starting, since the angular speed is larger when the motor is already rotating? is back emf constant or variable? if the metallic core causes eddy current that leads to energy loss, then why we don't use coils with empty core? 


#6
Mar1611, 03:55 PM

P: 97

what causes Inrush current drawn by an electrical device when first turned on in case we are supplying the device AC current?
is the phenomenon of self induction exists in motors?? are all these "back emf, self induction, eddy current" exist in a an electrical motor? is the energy consumed by back emf equals the energy transformed from electrical state to mechanical state? 


#7
Mar1611, 04:35 PM

P: 97

i have read that coils with iron core have variable inductance according to the variation of current, is there any formula that relate the variable L with I???
C = Q/v is there any proof for this formula??? thanks in advance 


#8
Mar1611, 10:42 PM

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#9
Mar1711, 08:37 AM

P: 97

what causes Inrush current drawn by an electrical device when first turned on in case we are supplying the device AC current?
is the phenomenon of self induction exists in motors?? are all these "back emf, self induction, eddy current" exist in a an electrical motor? is the energy consumed by back emf equals the energy transformed from electrical state to mechanical state? i have read that coils with iron core have variable inductance according to the variation of current, is there any formula that relate the variable L with I??? C = Q/v is there any proof for this formula??? thanks in advance 


#10
Mar1711, 11:53 AM

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#11
Mar1711, 01:05 PM

P: 97

then how could we calculate the energy transformed from electrical state to mechanical state in an electrical motor??



#12
Mar1711, 01:18 PM

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#13
Mar1711, 01:28 PM

P: 97

i can't understand how an eddy current brake works, may u illustrates it to me or give me any links that explains it simply with animated images. actually i understand what eddy current is in a motor, but how could it be used as a brake?
thanks for helping me 


#14
Mar1711, 05:07 PM

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The same principle is used for regenerative braking in hybrid cars such as the Prius, except that the energy generated in braking is used to recharge the battery rather than generate waste heat. AM 


#15
Mar1811, 03:00 PM

P: 97

what causes inrush current when an electrical device is turned on???



#16
Mar1811, 09:45 PM

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#17
Mar1911, 01:15 PM

P: 97

"If the motor was frictionless and superconducting, it would use no power. This is because the back emf opposes the imposed voltage."
in this case, will the motor keep on spinning? will the current keep on traversing the armatures? if yes, how this would happen without consuming any energy i.e with no power? can you tell me what this calculation give us : back emf*current=??? 


#18
Mar1911, 01:28 PM

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