Basic inductor question

How is it that the winding direction of a coil whether it is CW or CCW has no effect on the direction of the induced voltgae. When we analyze a circuit we always do v = Ldi/dt, however according to the right hand rule, depending on the current direction, the field direction will have one of two orientations.

Can someone shed a light on how this works?

Reply to
M. Hamed
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The winding direction "cancels out".

A current creates a field. A changing field creates a voltage.

If you change the winding direction, you negate both of the relationships, resulting in no change overall.

Reply to
Nobody

Hello Hamed. Imagine a pancake coil, grounded at the center with a positive voltage applied to the outer lead. You can pull the center out like a slinky in either direction. It won't change the orientation of the magnetic lines. Or say you are winding a toroid oriented with its axis vertical, and you start by laying a wire over the top of the toroid, pulling it down through the center and back toward you from underneath. It then matters not whether you continue the windings leftward or rightward around the toroid (this is the same statement, in principle, as the pancake coil). Looking at two toroids wound in this way, you would probably say they are wound in opposite directions. But that ignores phasing. You have a dot at the end of the wire you started with. If you now compare the two toroids, INCLUDING THE PHASING DOT, you will see that they have the same handedness.

Reply to
Michael Robinson

Firstly, lets's get the nomenclature straight. CW and CCW refer to a planar surface viewed from one side only; if you were behind a transparent clock, the hands would move CCW as you watched. In terms of a flat-wound coil, the difference between CW and CCW includes the choice of which of the two terminals you 'start' from, there's NO other meaning.

When looking at mutual inductors, the orientation of the magnetic field does depend on the current injected, and does so by the right-hand-rule (because we defined field direction that way). So, there's a polarity change if you inject the current in one or the other terminal, but it's the polarity of the FIELD (i.e. it's a three- dimensional vector, with orientation and magnitude). The 'V =3D L di/dt' equation doesn't have any field-vector orientation dependence.

The second winding of a transformer, though, DOES have an orientation dependence, usually a polarity with respect to the primary winding.

Reply to
whit3rd

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