Electric Motors

Hi,
I am taking a course on electric motors and i have a couple of questions.
1) When you have a wire and you loop it through an iron bar, what
causes the iron bar to become a magnet? 2) What does induced emf mean?
Thanks
Harish
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On Sat, 16 Feb 2008 18:52:08 -0800 (PST), Harish

When you pass current through a wire it generates a magnetic field, winding the wire around an iron core makes that field add up 1x per turn

When you stop passing current through that wire the field you built up collapses and gives that energy back to the wire, usually very quickly with a "spike" in the voltage. That is how the spark coil works in a car.
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Try: http://www.allaboutcircuits.com/vol_2/chpt_10/4.html
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read a textbook. if u don't understand something specific in the textbook, try asking ur friends on the course...or your teacher. there's loads on the web. if ALL else fails post the question here.
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