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msirshad · Dec 1, 2005, 12:50 PM

What happens inside a transformer that increases or decreases the voltage?When a transformer steps up voltages,from where it creates thes voltages?

fredg · Dec 1, 2005, 12:58 PM

Hi,
When a transformer steps up the voltage, it creates it from a electromagnetic field.

Here is a good site for an explanation; with pictures:

http://www.circuit-innovations.co.uk/transformers.html

Best wishes.

shanus · Jan 2, 2006, 02:48 AM

There is a famous law that you should learn... V = I*R

voltage is equal to current times resistance.
to increase the voltage either the current must increase or the resistance must increase.

nikitesla · Feb 2, 2009, 12:12 PM

Originally Posted by msirshad

What happens inside a transformer that increases or decreases the voltage?When a transformer steps up voltages,from where it creates thes voltages?

A transformer is a device that "transforms" the alternating electrical current at one voltage (on the input winding) to another voltage at the output winding, by the proportional number of turns on the input winding compared to the output winding. If you are wondering how is it possible to produce a higher voltage from a device where no additional energy is added other than the input power itself the answer is that, with an increase in output voltage there is a proportional loss of output current. So for instance if there are 1000 turns on the primary with an input voltage of 120VAC Root Mean Squared (RMS) at 1 amp then if the secondary had 2000 winds it would have 240VAC at the output with a little less than 1/2 amp of available current. So that there is a 1 to 1 transfer of energy with some 1-5% lost in eddy currents through the core of the transformer, but a net increase (doubling of voltage and proportional loss of available current. Volts x Amps = watts. I.E. 120Volts at 1 amp in = 120Watts, and 240V at 1/2 amp, out, also = 120 Watts. In this example perhaps 3 watts may be lost as eddy current heating the core (often transformers are 98-99% efficient at rated power) so the available current would be about .490 amps before the supplied output voltage begins to sag under load.