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The ampere is an SI base unit and electric current is a base quantity in the International System of Quantities (ISQ). [4]: 15 Electric current is also known as amperage and is measured using a device called an ammeter. [2]: 788 Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers.
Electricity plays a central role in many modern technologies, serving in electric power where electric current is used to energise equipment, and in electronics dealing with electrical circuits involving active components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies.
The first half of the 700-page book is a history of the study of electricity. It is parted into ten periods, starting with early experiments "prior to those of Mr. Hawkesbee", finishing with variable experiments and discoveries made after Franklin's own experiments.
The war of the currents was a series of events surrounding the introduction of competing electric power transmission systems in the late 1880s and early 1890s. It grew out of two lighting systems developed in the late 1870s and early 1880s; arc lamp street lighting running on high-voltage alternating current (AC), and large-scale low-voltage direct current (DC) indoor incandescent lighting ...
Streetcars created enormous demand for early electricity. This Siemens Tram from 1884 required 500 V direct current, which was typical. Much of early electricity was direct current, which could not easily be increased or decreased in voltage either for long-distance transmission or for sharing a common line to be used with multiple types of electric devices.
Italian physicist and electrical engineer Galileo Ferraris publishes a paper on the induction motor, and Serbian-American engineer Nikola Tesla gets a US patent on the same device [4] [5] 1890: Thomas Alva Edison invents the fuse: 1893: During the Fourth International Conference of Electricians in Chicago, electrical units were defined 1893
In the 19th century it had become clear that electricity and magnetism were related, and their theories were unified: wherever charges are in motion electric current results, and magnetism is due to electric current. [3] The source for electric field is electric charge, whereas that for magnetic field is electric current (charges in motion).
A simple electromagnet, consisting of an insulated wire wound around an iron core. An electric current passing through the wire creates a Magnetic field, with a north pole at one end and a south pole at the other. The first application of electricity that was put to practical use was electromagnetism. [18]