Electromotive Force and Potential Difference

Emf and P.d

You should be able to:(a) define potential difference (p.d.);(b) select and use the equation W = VQ;(c) define the volt;(d) describe how a voltmeter may be used todetermine the p.d. across a component;(e) define electromotive force (e.m.f.) of a sourcesuch as a cell or a power supply;(f) describe the difference between e.m.f. and p.d in terms of energy transfer

Circuit Symbols

• Draw any circuit symbol that you can remember. ( there are 16 that you need to know)

Emf and P.d

Emf and Potential difference are about energy

Emf and P.d

Emf and P.dElectromotive force is the energy transferred per coulomb when one other type of energy is converted into electrical energy.

This tells us that emf :• Is measured in joules per coulomb

• That it always deals with the supply of electrical energy.

Emf and P.d

Emf and P.d

Potential difference is the electrical energy transferred per coulomb when electrical energy is converted into another form of energy.

This tells us that pd :• Is measured in joules per coulomb

• That it always deals with the use of electrical energy.

Emf and P.d

V = W Q

Emf and P.d12V

3V 9V

Describe in terms of energy what is happening in this circuit.