I have a small wall plug which takes 240V 50Hz AC from the mains, and can give me 500mA 5V DC. I suspect there is a transformer stepping the voltage down and a bridge rectifier converting the AC to DC.
BUT... the amount of current which flows... how is it controlled?
I know that if I plug in a 3KW heater, that the electrical cable gets quite warm from all the current flowing through it, but the cable on a phone charger does not.
Is it to do with every mains socket being a parallel load? i.e. if everyone on the national grid unplugged every appliance at the same time, apart from my charger, would my charger explode?