🚀 go-pugleaf

In article <3571B56A.3563@senet.com.au>, Wee-Kiat Kong
<wkkong@senet.com.au> writes
>I'm doing as assignment for Physics about induced EMF and I have to describe 
>how a transformer works.
>
>My problem is that I don't quite understand what the iron core in 
>transformers actually do. Does an alternating current get induced in the core 
>due to the magnetic field caused by the primary coil's alternating current? 
>Does it (the iron core) therefore create another stronger magnetic flux which 
>induces an EMF in the secondary coils?
>
>Also how is the direction of the current in the iron core and the 
>secondary coil determined?
>
>Please reply by e-mail and the newsgroup.
>
>Thank you in advance.
>
>Wee-Kiat
O.K. Thumbnail sketch coming up
Dierction of magnetic field in iron core is dictated by right hand grip
rule. " Hold core in your right hand with your finger curled round in
the direction of the current flow. Your outstrecthed thumb will point in
the direection of action ( North ) of the field.  Because the current
alternates ( reverses direction) the the field also reverses direction.

From Flemming's original experiments we know that it matters nought
whether the field moves or the coil moves as long as the flux is
changing an e.m.f. will be generated.  Note it is the constantly
changing flux which generates the e.m.f. in the secondary, hence it does
not work with D.C.
The magnetic flux density is the same in both sides of the core and is
dictated by the permeability of the core and the current X the number of
turns on the primary.  The e.m.f from the secondary is dictated by the
ratio of turns from primary to secondary. ( primary 100 turns secondary
200 turns, output       e.m.f = 2 x input voltage)  You now need to find
out about iron losses, copper losses and eddy currents. 
-- 
Ken Smith   
http://www.kencom.demon.co.uk/
        "Time is an illusion, lunch time doubly so"  Ford Prefect