Electricity & Magnetism

This is the extraordinary story of the development of our understanding of electricity and magnetism; from Coulomb’s measurement of the force between two electric charges using a torsion balance in 1785; Volta’s construction in 1799 of the first electrochemical battery, known as a voltaic pile; the discovery of the link between electricity and magnetism by Ørsted in 1819; their combination in the electromagnetic wave theory of light in Maxwell’s extraordinary papers, between 1855 and 1865; the recognition that an electric current comprises a flow of free electrons based on Bohr’s 1913 theory of the atom; and finally Heisenberg’s brilliant demonstration in 1928 that ferromagnetism is a quantum entanglement effect resulting from the spin of the electron and the structure of the molecular lattice. Oliver Heaviside’s story is a gem. Part I describes what is general understood by electricity and magnetism. Part II provides a record of the discoveries and the resulting theories prior to Maxwell’s papers on electromagnetism. Part III addresses electromagnetic radiation. Part IV reviews the explanation of electrical and magnetic phenomena in terms of the motion and spin of charge particles and quantum theory.