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An electric battery is a source of electric power consisting of one or more electrochemical cells with external connections [ 1] for powering electrical devices. When a battery is supplying power, its positive terminal is the cathode and its negative terminal is the anode. [ 2] The terminal marked negative is the source of electrons that will ...
Electric charge (symbol q, sometimes Q) is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be positive or negative. Like charges repel each other and unlike charges attract each other. An object with no net charge is referred to as electrically neutral.
In physics, charge conservation is the principle that the total electric charge in an isolated system never changes. [ 1] The net quantity of electric charge, the amount of positive charge minus the amount of negative charge in the universe, is always conserved. Charge conservation, considered as a physical conservation law, implies that the ...
1871–1879. Succeeded by. Lord Rayleigh. Signature. James Clerk Maxwell FRS FRSE (13 June 1831 – 5 November 1879) was a Scottish physicist with broad interests [ 1][ 2] who was responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and light as different manifestations ...
v. t. e. In electromagnetism and electronics, electromotive force (also electromotance, abbreviated emf, [ 1][ 2] denoted ) is an energy transfer to an electric circuit per unit of electric charge, measured in volts. Devices called electrical transducers provide an emf [ 3] by converting other forms of energy into electrical energy. [ 3]
Wireless power transfer. Inductive charging pad for a smartphone as an example of near-field wireless transfer. When the phone is set on the pad, a coil in the pad creates a magnetic field [ 1] which induces a current in another coil, in the phone, charging its battery. Wireless power transfer ( WPT ), wireless power transmission, wireless ...
History of the battery. Batteries provided the primary source of electricity before the development of electric generators and electrical grids around the end of the 19th century. Successive improvements in battery technology facilitated major electrical advances, from early scientific studies to the rise of telegraphs and telephones ...
Abstract definition. Abstractly, a charge is any generator of a continuous symmetry of the physical system under study. When a physical system has a symmetry of some sort, Noether's theorem implies the existence of a conserved current. The thing that "flows" in the current is the "charge", the charge is the generator of the (local) symmetry group.