Past exam of the short options paper shared by Prelims and Parts A and B of the physics course of the University of Oxford / 2018 / S14 / 3

Michael Faraday established new electrical phenomena through carefully varied experiments and made the field a central explanatory concept. His achievements were not confined to a single apparatus or to applications later expressed in equations by other researchers.

In 1821 he demonstrated continuous electromagnetic rotation: a current-carrying conductor could move around a magnet, or a magnet around a conductor, with the current maintained through an appropriate contact. The circular motion was difficult to reduce to an ordinary static attraction along a line and provided an experimental route toward electric-motor action.

In 1831 his induction experiments linked changing magnetic conditions to an induced electrical response. In the ring-coil arrangement, switching current in one winding produced a transient deflection in the other winding rather than a persistent response to a steady current. Moving a magnet relative to a coil produced a related effect. Comparing these arrangements helped identify change of magnetic linkage, rather than mere proximity to a magnet, as the essential feature. His rotating-disc generator showed a further way to obtain electrical output from mechanical motion.^[ref]

His electrolysis studies established quantitative relationships between charge transferred and material deposited or liberated. These supported a connection between chemical change and definite electrical quantities, even though they did not yet amount to a modern atomic theory of charge. His work on dielectrics and electrostatic shielding examined how materials and conducting boundaries influence electrical effects.

In 1845 he observed magnetic rotation of the plane of polarization in a material and investigated diamagnetism. The magneto-optical effect gave experimental evidence for a connection between light and magnetism, while diamagnetism showed a response opposite to ordinary magnetic attraction. Those findings broadened electromagnetism beyond currents and permanent magnets.^[ref]

Faraday's lines of force emphasized processes in the intervening region rather than only direct action at a distance. James Clerk Maxwell subsequently converted crucial parts of that field conception into a mathematical electromagnetic theory. Calling Faraday merely an unmathematical precursor would miss the explanatory and experimental content of his field ideas; crediting him with Maxwell's completed equations would be equally inaccurate. His legacy combines new effects, reproducible experimental techniques, quantitative electrochemistry and a fertile physical picture of fields.