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An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated along the center of the coil. The magnetic field disappears when the current is turned off.
The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interactions of atoms and molecules. Electromagnetism can be thought of as a combination of electrostatics and magnetism, which are distinct but closely intertwined phenomena. Electromagnetic forces occur between any two charged particles.
The existence of electromagnetic radiation was proved by Heinrich Hertz in a series of experiments ranging from 1886 to 1889 in which he discovered the existence of radio waves. The full electromagnetic spectrum (in order of increasing frequency) consists of radio waves, microwaves , infrared radiation , visible light , ultraviolet light , X ...
The definitions for monopoles are of theoretical interest, although real magnetic dipoles can be described using pole strengths. There are two possible units for monopole strength, Wb (Weber) and A m (Ampere metre). Dimensional analysis shows that magnetic charges relate by q m (Wb) = μ 0 q m (Am).
In addition to the mentioned classic books, in recent years there have been a few well-received electromagnetic textbooks published for graduate studies in physics, with one of the most notable being Modern Electrodynamics by Andrew Zangwill published in 2013, which has been praised by many physicists like John Joannopoulos, Michael Berry, Rob ...
This led William Sturgeon to develop an iron-cored electromagnet in 1824. [7] Joseph Henry further developed the electromagnet into a commercial product in 1830–1831, giving people access to strong magnetic fields for the first time. In 1831 he built an ore separator with an electromagnet capable of lifting 750 pounds (340 kg). [13]
Electricity and Magnetism is a standard textbook in electromagnetism originally written by Nobel laureate Edward Mills Purcell in 1963. [1] Along with David Griffiths' Introduction to Electrodynamics, this book is one of the most widely adopted undergraduate textbooks in electromagnetism. [2]
A Bitter electromagnet or Bitter solenoid is a type of electromagnet invented in 1933 by American physicist Francis Bitter used in scientific research to create extremely strong magnetic fields. Bitter electromagnets have been used to achieve the strongest continuous manmade magnetic fields on earth―up to 45 teslas , as of 2011 [update] .