b) Electromotive force

b) electromotive force (e.m.f.) of a source such as a cell or a power supply

c) the distinction between e.m.f. and p.d in terms of energy transfer

d) energy transfer; W = VQ; W = εQ

potential difference → when work is done by charge carriers on a component → charge carriers are losing energy

electromotive force → when work is done to charge carriers by a component (cell, battery, or power supply) → charge carriers are gaining energy

electromotive force = the joules of chemical energy transferred from the component to the electrical store of one coulomb of charge

ε = W / Q

• electromotive force of a component (V) = chemical energy transferred from the component (J) / charge (C)