why is current produced in a coil if it is placed near other current caarrying coil
If a current is run through a coil, it will produce an electromagnetic field around the coil. If a different coil is placed inside that field, the electromagnetic field from the first will induce a current in the second.
with the important point that the current in the first coil must be alternating ( oscillating)
ie. if it is a non varying DC current, there will be no induced voltage/current into the second coil
He hasn't asked question clearly but he was mean that what happen if two coil both are supplied power placed near?
Hello Alph and welcome.. sorry but your comment was not clear at all.
that just doesn't make sense at all
but how actually is the current produced
have a read up on transformer theory ......
Here is a transformer thread. Two coils near each other ia essentially a transformer.
See: Maxwell Equations. They'll give you the answer you want much more eloquently and clearly than I can.
One of the benefits of this topic is that it can be broken down into smaller parts:
1) Current flow produces a magnetic field - even when you pass DC current though a conductor, or a wrapped coil of conductors, at the initial "turn on" the magnetic field is changing, once the DC current has reached steady state - the magnetic field is no longer changing - but is still there!
2) A changing magnetic field will induce a current in a conductor that intersects the conductor. This is induction -- if we move a conductor through a static (non-changing ) field we induce current. (permanent magnet generator with stationary magnets and moving windings) - if we hold a conductor stationary and move the magnet (field), current is also induced.
Commonly described as when magnetic flux lines* cut through a conductor current is induced. ( the purists here will be offended by the notion of magnetic flux lines - however that is the common introduction - they are not truly lines - the Mag Field is continuous, personally I suppose this notion comes from studying magnetic with iron filings - when you do this you see lines - but I digress... )
So in general we look at (study) creating magnetic fields - with magnets or with electromagnets-- once the field is established it does not matter HOW it is created.
OK - now take a conductor or coil (coil A), and turn the current on and off... you can understand you are creating and stopping a magnetic field. If you reverse the current the magnetic field is also reversed.
Now put another conductor or coil (coil B) - in the area of Coil A above (physical alignment of the conductors or coils does matter )... as the magnetic flux from coil A is not expanding and collapsing -- it is intersecting whit the Conductors in Coil B, this magnetic field induces current in Coil B.
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