Transformer question from student.

Hello, this may be a difficult question to word, but I'll try. I'm here to learn!

I have a moderate understanding of how a transformer works. A magnetic field from one set of windings evokes a voltage on the other, generally.

Let's say I have a 1:1 transformer; I put 10 VAC in and get 10VAC out. Lets say that the circuit on the output side pulls 5 amps. This means that the transformer will be pulling 5 amps on the input side of things, correct? My question is, how does this happen? I mean, this primary side is completely independent (physically) of the output, secondary side. Why does it "know" that the other side is pulling 5 amps, forcing it to "give" 5 amps?

I'm sorry for the layman's terms in this question, but I hope someone will understand what I'm trying to say.

I'm guessing that this has something to do with the tendency of a motor to draw more amperage when the output shaft is encountering difficulty?

Transformers allow the transfer of an AC signal from one circuit to another. The transfer may involve stepping up the voltage, stepping down the voltage, or passing the voltage unchanged.
If two electrically isolated coils are placed next to each other and an AC voltage is put across one coil, a changing magnetic field results. This changing magnetic field induces a voltage into the second coil. This action is referred to as electromagnetic induction. The device is called a transformer.
In a transformer, the coil containing the AC voltage is referred to as the primary winding. The other coil, in which the voltage is induced, is referred to as the secondary winding. The amount of voltage induced depends on the amount of mutual induction between the two coils.
When a load is connected across the secondary winding, as shown in the figure, a current is induced into the secondary. Transformers are wound with the secondary on top of the primary. The magnetic field created by the primary current cuts the secondary windings. The current in the secondary establishes a magnetic field of its own. The expanding magnetic field in the secondary cuts the primary turns, inducing a voltage back into the primary. This magnetic field expands in the same direction as the current in the primary, aiding it and causing it to increase, with an effect called mutual inductance. The primary induces a voltage into the secondary and the secondary induces a voltage back into the primary.

So the secondary coil's magnetic field induces a current on the primary side?

yes. the magnetic field induce aids to increase the current to the primary side.

check out http://generalpac.com - they have great videos tutorials that give you a better understanding of the actual transformer connections.

Hope this helps!

Hi dear,actually transformer is an energy conversion device,,and also a constant power device...so..if voltage on the secondary side decrease,current increases from primary side.But this current is produced in accordance with the mutual induction takes place in secondary side and with the secondary voltage...If it is 1:1 transformer,since voltage on secondary is same as in primary..so current is secondary is accordance with primary...ie 5 amps...