AC x DC

It's not that rock band name. It's the tipe of existant currents. You'll see now why does we have these two.

AC- Alternating Current

I'm sure that you can read, eh? The AC current is the current that pass through the electrical posts and through your walls and through the plug devices, and so on. Why does it exist? The men of the electrical company fond much better because you don't have too muc disperdice. The resistance is less.

This name means that this sort of currents alternates. Sometimes it's positive in one side and negative in other. Then it changes to negative in the first side and positive in the second. If you count it you'll have 60 changes in one second( this is where I live; it can vary in one place to other)!!!

The alternating current is represented by the ~ symbol.

DC- Direct Current

The direct current is there in bateries. It exitst becuase it's uniform. It doesn't have peaks of voltage. It's always from negative to positive.