Electricity and Magnetism

action alternate current apparatus arc lamps armature arranged attracted aurora axis ball battery bobbin body carbon cell centimetres centre charge circuit clouds coil communication compass conductor connected copper cylinder described diameter direction disc disk distance dynamo earth effects electric current electric discharge electric light electrified electromagnet electromotive force electroscope employed experiments fixed galvanometer glass Gramme machine hailstones horizontal increase induced currents induction influence instrument insulated intensity lamp layer lever Leyden jar liquid luminous machine magnetic needle magnetised mechanism mercury meridian metal millimetres mirror galvanometer motor movement negative pole observed opposite oscillations particles passes pendulum phenomena photophone piece placed plate platinum polar auroras positive produced receiver repelled repulsion rotation round secondary seen shows signals soft iron spark substances surface telegraph telephone theory transmitter traversed tube turn vertical vibrations voltaic voltaic arc wheel whilst wire zinc