A-Level Physics OCR A H556

4.2.2: E.m.f. and p.d

#4.2.2a

potential difference (p.d.); the unit volt

#4.2.2b

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

Epsilon is used as the symbol for e.m.f. to avoid confusion with E which is used for energy and electric field. The ASE guide ‘Signs symbols and systematics’ details E as the correct symbol for e.m.f. and this will be credited in all examinations.

#4.2.2c

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

#4.2.2d

energy transfer; W=VQW = VQ; W=εQW = εQ

#4.2.2e

energy transfer eV=12mv2eV = \dfrac{1}{2}mv^2 for electrons and other charged particles.

4.2.1
Circuit symbols
4.2.3
Resistance