Hello, Roar2lion! Welcome to Wikipedia! Thank you for your contributions to this free encyclopedia. If you decide that you need help, check out Getting Help below, ask me on my talk page, or place {{helpme}} on your talk page and ask your question there. Please remember to sign your name on talk pages by clicking or using four tildes (~~~~); this will automatically produce your username and the date. Finally, please do your best to always fill in the edit summary field. Below are some useful links to facilitate your involvement. Happy editing! DuncanHill13:21, 17 October 2007 (UTC)[reply]
In response to your note on my talk page, a transformer does not work as you describe. The primary current of a transformer is much smaller when no current flows in the secondary, and more primary current flows when more current is taken from the secondary. This is because the windings are magnetically coupled. When the secondary is not connected to anything (open) then the primary acts as an inductor, with the large number of primary turns around a ferrous (iron) core. If the inductance is high (as is the case in a power transformer or most other transformers) due to having a core of substantial cross section with lots of turns of wire, then the no-load current is fairly low, called "magnetizing current." If there were no magnetic core, then the current would be very high, limited only by the resistance of the primary winding. The current from the primary produces a magnetic field which changes rapidly, since it is alternating current. This magnetic field is caused by the iron core to stay tightly surrounding the core and the primary winding and the secondary winding. It produces a voltage in the secondary winding, proportional to the number of turns in the secondary winding. A "counter-emf" (electromotive force, or voltage) is set up in the primary winding by the magnetic field in the core, and this self-inductance is what prevents a heavy flow of current in the primary of a transformer with no secondary current, the same as in any other inductor. If a load is placed on the secondary winding, it decreases the magnetic field, decreasing the counter emf, and allowing more current to flow in the primary. That is how power gets transferred from the primary to the secondary of a transformer. Please read and re-read Transformer. Edison (talk) 13:43, 28 October 2008 (UTC)[reply]
