[SOLVED] Transformation 220V-5V

[ororo]

Hello,
this is just a curiosity. I am wondering if it is possible to transform a 220V AC current into a 5V AC current just using a resistor. Such a resistor should have, I guess, about 215 ohm for achieving a current of 1A. The problem is heat dissipation. The resistor should resist a power of about 215 W. Does any such resistor exist?

 

[Dominik Przyborowski]

Yes, their exists.
But making voltage divider to achieve 5V from 220V dissipating over 200W of power is stupid ;-)
For this reason we using transformers

 

[BradtheRad]

Since we are talking about reducing AC...

There is also the method of reactive drop. That is, by capacitor or inductor. These do not generate heat, whereas resistive drop does.

However reactive drop does create power factor inefficiencies (although these can be remedied).

 

[ororo]

@BradtheRad , I am trying to understanding your answer, but I have some trouble.
If we use a capacor or an inductor, the (average) voltage reduces, but what does it happen with power? What kind of inefficiences are you talking about? I would like to read more about it, but I don't know where to begin.

Thank you.