Electromagnetic induction and energy conservation

[Hemal Pansuriya]

1 hour ago, swansont said:

Transformers don't violate conservation of energy. You trade current for voltage, one direction or the other. But the power is constant. P=IV

If you attach at transformer to a coil then the load changes. You've assumed that the only impedance is resistive.

I know transformers don't Violate energy conservation law...power in primary and secondary will be the same.....but by using transformer you can draw more power by the following way :  if voltage induced in coil is varying with time than use coil as voltage source and connect it to transformer's primary coil suppose voltage produced in coil is V, then step up this voltage by factor of 1000 ( or arbitrarily large ). Suppose resistance connected in secondary is R, so current in secondary winding will be I =1000V/R. And in primary winding current will be drawn 1000*I ( because IpVp=IsVs ). So now the power output of the coil will be V*(1000*I).So now the power output of the coil will be V*(1000*I) . We have drawn 1000 times more power than previously, which was V*I.

[John Cuthber]

Yes, and, to do it, you have to feed a thousand times more power into the transformer.

So what?

You could achieve the same outcome by just connecting a lower resistance to the power supply. (I'd need to check, but I think it's a "square root of 1000" times smaller resistance.)

The second option is almost certain to be cheaper.

Edited October 22, 2017 by John Cuthber

[Hemal Pansuriya]

1 hour ago, John Cuthber said:

Yes, and, to do it, you have to feed a thousand times more power into the transformer.

No, we don't have to. Because, magnet is not going to feel resistance during delay period.