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Magnetic field produced by a solenoid (coil of wire). This drawing shows a cross-section through the center of the coil. The crosses are wires in which current is moving into the page; the dots are wires in which current is moving up out of the page. A common tractive electromagnet is a uniformly wound solenoid and plunger.
The electric field sends the electron to the p-type material, and the hole to the n-type material. If an external current path is provided, electrical energy will be available to do work. The electron flow provides the current, and the cell's electric field creates the voltage. With both current and voltage the silicon cell has power.
Production of electric current from a moving magnetic field was demonstrated by Faraday in 1831. The first machines to produce electric current from magnetism used permanent magnets; the dynamo machine, which used an electromagnet to produce the magnetic field, was developed later.
Magnets can be used in scrap and salvage operations to separate magnetic metals (iron, cobalt, and nickel) from non-magnetic metals (aluminum, non-ferrous alloys, etc.). The same idea can be used in the so-called "magnet test", in which a car chassis is inspected with a magnet to detect areas repaired using fiberglass or plastic putty.
These so-called ceramic magnets are cheap, and are widely used in household products such as refrigerator magnets. The maximum magnetic field B is about 0.35 tesla and the magnetic field strength H is about 30–160 kiloampere turns per meter (400–2000 oersteds). [33] The density of ferrite magnets is about 5 g/cm 3.
In addition, relativity theory implies that in moving frames of reference, a magnetic field transforms to a field with a nonzero electric component and conversely, a moving electric field transforms to a nonzero magnetic component, thus firmly showing that the phenomena are two sides of the same coin. Hence the term "electromagnetism".
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Electromagnetic launchers are electric projectile weapons that use a magnetic field to accelerate projectiles to a very high velocity. These launchers require high power pulse sources in order to work. These launchers can be realised by the use of the quick release capability and the high power density of the SMES system. [21]