You can measure current and potential difference in circuits. ... For example, 230 V is a bigger potential difference than 12 V. ... A circuit diagram showing a voltmeter in parallel with a lamp.

Learn how electric circuits work and how to measure current and potential difference with this guide for KS3 physics students aged 11-14 from BBC Bitesize.

Vectors and Vector Diagrams applied to the Alternating Current Circuit. By W. Cramp C. F. Smith. Pp. xvi + 252. (London: Longmans, Green and Co., 1909.) ...