Current b4 and after load

Suppose you have 220 volts AC and a load such as an electric fan. Is the current before and after the load exactly 100% similar in value? Are there loads wherein the current can become different before and after the load. If they are all 100% exactly the same. How come the two parallel electric cord glued together commonly used in appliances still has residue magnetic field (like 1.5mG) and they don't cancel 100%. They theoretically should since the current before and after the load is exactly the same so the magnetic field is exactly 180 degrees out of phase so 0 mG output should suppose to occur.

Thanks.

Dave

Reply to
Dave
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If the currents were not identical where the difference current go?

Radiated.

Reply to
R.Lewis

At what portion of the circuit does it have possibility of radiating? The circuit is just composed of an electric bulb and wires plug to AC. You mean the bulb radiate the missing current as EM?

Dave

Reply to
Dave

Current in is same as current out. That is the LAW. The magnetic fields do not cancel exactly because they are not occupying same space.

Try this for fun:

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Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

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Reply to
Boris Mohar

fields do

I see. In a typical electrical cord, there is a few distance in mm between the 2 parallel wires with opposing magnetic field. So not all magnetic field cancel as you say. Do you know of a drawing or illustration in a site of the residue magnetic field produced or an illustration of the graphics of the magnetic field being in the act of being canceled. Thanks.

Dave

Reply to
Dave

I do not wish to sound terse but when you get through that book at the website I recommended you will be able to make your own drawing. If you are really thorough with the book you will not need the drawing.

--

    Boris Mohar
Reply to
Boris Mohar

If one wire has a leak to ground, the current after the leak is lower. Generally it woiuld be the hot wire; the other one is at ground already. You can buy a GFI ground fault interrupter. It takes both currents through opposed windings in a relay, but with a leak, the current difference opens the relay to prevent shock. John Polasek

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Reply to
John C. Polasek

Apologies. My response was rhetorical in that if the currents were not equal the difference current must be radiated else there must be a mechanism to 'store' an infinite amount of current in your load (electric fan). Since if the fan was left on a long time this would store all the electrons in the universe we would have a problem. Since it isn't radiated the currents must be the same.

.
Reply to
R.Lewis

electrons

the currents would be the same even if it was radiated. as you said, the electrons are not destroyed, so they have to be the same unless there is a third path for them to get back to the source... such as a ground fault in the device.

Reply to
Dave

Dave schrieb:

...

Nevertheless the current which flows into the fan is equal to the current which leaves the fan. It has nothing to do with the _way_ the current takes when flowing out of the fan, e. g. partially along a leakage path.

HTH

Reinhard

Reply to
Reinhard Zwirner

-The currents are the same. The reason that there is a residual field is because the two current "filaments" are not exactly in the same location with respect to anything beyond the wires. The field at a distance r from one wire is proportional to I/r while that due to the other is due to I/(r+d) where d is the distance between the wires. Complete cancellation only occurs at points equidistant from both conductors.

--
Don Kelly
dhky@peeshaw.ca
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Reply to
Don Kelly

is

location

from

cancellation

I see. So if one wire has 10 mG, the second one has 10 mG opposite in vector, because they are not in the same position in space, there is a residual 0.8 mG left. Do you know a url that has illustration what part of the waveform are cancelled and what part of the waveform survives to create the 0.8 mG.

I wonder if the 0.8 mG left in the above configuration is 100% the same in waveform shape, etc. than a single wire that emit

0.8 mG. What do you think?

Dave

Reply to
Dave

Dave schrieb:

It depends upon _where_you_measure_ the residual magnetic field. There are points in the space around the wires where a complete cancellation occurs: with a punctiformly field sensor you'll find those points. In other points where the measuring device isn't equidistant to the wires you'll measure the difference between the "to-field" and the "fro-field" at that point. Okay?

HTH

Reinhard

Reply to
Reinhard Zwirner

------------- The above question is partially meaningless- field at a point has no "shape" It has direction and magnitude- At any given point, the direction of the field and its magnitude will not be the same as that due to a single wire.

I don't have a site but it is easy to work it out for a particular situation. For example consider a 0.5 mm wire centered at 0,0 and another at 2, 0 with the currents equal and opposite. B1=mu0I/r for r>0.5 (muoI*r for 0

Reply to
Don Kelly

Another way to think of it is as an inductor. Imagine a loop of wire with X amperes flowing through the loop, and realize that the inductance can be computed as well as flux which would be proportional to the current and area enclosed. Now flatten the loop so the two wires are separated by D and if you still have an area enclosed, then you still have an inductance working and you still have a single current flowing and there will be a magnetic field present.. John Polasek

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Reply to
John C. Polasek

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