want to clarify my understanding of emf and pd
emf is the force supplied to drive the electrons to move whereas pd is the amount of emf that is used? which in turns can be converted to other forms of energy?

Question

anonymous · Answer

Emf is a voltage (= potential difference) generated by a battery or magnetic force. See: http://en.wikipedia.org/wiki/Electromotive_force So all emf:s are potential differences, but not all potential differences are emf. Emf refers to a potential difference caused by some energy source, like chemical reaction in a battery.