EMF, terminal p.d. and real cells
EMF, terminal p.d. and real cells

EMF is the energy supplied per unit charge by a source, so ε=WQ\varepsilon = \frac{W}{Q}ε=QW. It is measured in volts because 1 V=1 J/C1 \, \text{V} = 1 \, \text{J/C}1V=1J/C, but it is not a force.
Step-by-step lessons on Edexcel A Level Physics EMF and internal resistance. Each one builds up to exam-style questions. Physics is one of the most mathematically demanding A Levels -- at least 40% of the marks across the three papers require maths skills at Level 2 (GCSE) standard or above, so build calculation and graph-handling fluency alongside the conceptual content from the start.