I need to do a presentation for my physics class and I'd really like to understand the whole thing with coils and all that. We've got an old one in our garage that transforms the current from the meter, but I can't quite figure out why it changes the voltage. Can someone explain it to me simply?
A transformer really isn't complicated once you get how it works. You've got two coils of wire wrapped around an iron core. When alternating current flows through the first coil (the primary), it creates a magnetic field that's constantly changing. That magnetic field travels through the iron core and reaches the second coil (the secondary). Result: it induces current in the second coil without them needing direct contact. That's electromagnetic induction, and it's honestly key to understanding how this thing operates.
Now, why does the voltage change? It depends on how many turns each coil has. If the secondary has fewer turns than the primary, you get lower voltage. If it has more, you boost the voltage. Basically, primary voltage / secondary voltage = primary turns / secondary turns. So that old thing in your garage that transforms from the meter? It probably has way more turns on the input side to step down the high grid voltage and make it usable for you at home.
The important thing is it only works with AC, not DC. With DC, there's no changing magnetic field, so nothing happens. And without the iron core to channel the magnetism from one coil to the other, it'd be way less efficient. There you go - that should be enough for your presentation, good luck.
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