warning lamp with Euro lights

[Robert Myers]

--
You are correct that a steady magnetic field surrounds a wire carrying a
steady electric current.  But what is required for that magnetic field to
drive a current in a secondary wire is for that wire to cut through the
magnetic field or, alternatively, for the magnetic field to cut through the
secondary wire.  The first is what the alternator of your car does.  A coil
of wire is turned within a magnetic field generating an alternating
current.  The second is what a transformer does.  The primary (field
producing) coil of wire and the secondary cold of wire do not move relative
to each other but the magnetic field of the primary repeatedly expands and
collapses as the alternating current in the primary passes through its
sinusoidal variations.  This expanding and collapsing causes the magnetic
field to cut through the secondary coil inducing an alternating voltage
(and assuming a complete connection, an alternating current) in the secondary.

Transformers work only for AC, not DC.

At 07:18 AM 11/13/01, scott miller wrote:

>>Bad theory.  You will only get a current in your coil when the current >in
>>the wire _changes_.
>
>Really?  I thought that was how transformers worked - cascading magnetic
>fields driving electrons in parallel wires as the powered wires change
>current (AC).  Doesn't the steady magnetic field circling a steady flow of
>electrons in a wire (DC), drive electron flow in a circle of wire around the
>first wire?  Guess I'll have to get out the books.
>
>Scott
>still not an EE
>
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Bob
*****
  Robert L. Myers   304-574-2372
  Rt. 4, Box 57,  Fayetteville, WV 25840 USA   WV tag Q SHIP
  '95 urS6  Cashmere Grey - der Wunderwagen    ICQ 22170244
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