Lecture 20
... Thermoelectric properties In the independent electron approximation good electrical conductors are also good conductors of heat, since the conduction electrons transport entropy as well as electric charge. Superconductors are poor thermal conductors. An electric current at uniform temperature in a ...
... Thermoelectric properties In the independent electron approximation good electrical conductors are also good conductors of heat, since the conduction electrons transport entropy as well as electric charge. Superconductors are poor thermal conductors. An electric current at uniform temperature in a ...
19.- Modeling Electromagnetic Fields in Induction Heating
... eddy currents are induced in the treated component without the need of electrical contact. The induced currents together with the electrical resistance of the material result in localized heating by Joule effect. The resulting temperature field is then directly related to the electro-magnetic parame ...
... eddy currents are induced in the treated component without the need of electrical contact. The induced currents together with the electrical resistance of the material result in localized heating by Joule effect. The resulting temperature field is then directly related to the electro-magnetic parame ...
Magnetism - MAGNETRON2011-2012
... The ability of matter to attract matter to itself The ancient Greeks were the first to discover this phenomenon in a mineral they named magnetite ▪ First observed at least 2500 years ago in fragments of magnetized iron near the ancient city of Magnesia in Western Turkey ▪ These fragments are known a ...
... The ability of matter to attract matter to itself The ancient Greeks were the first to discover this phenomenon in a mineral they named magnetite ▪ First observed at least 2500 years ago in fragments of magnetized iron near the ancient city of Magnesia in Western Turkey ▪ These fragments are known a ...
magnetic field
... the generator changes direction each time the coil makes a half turn. Because the electric current changes direction, it is an alternating current. The energy that generators convert into electrical energy comes from different sources such as fossil fuels and nuclear energy. ...
... the generator changes direction each time the coil makes a half turn. Because the electric current changes direction, it is an alternating current. The energy that generators convert into electrical energy comes from different sources such as fossil fuels and nuclear energy. ...
Electro Magnet
... • The electric current produced by the generator changes direction each time the coil makes a half turn. Because the electric current changes direction, it is an alternating current. • The energy that generators convert into electrical energy comes from different sources such as fossil fuels and nuc ...
... • The electric current produced by the generator changes direction each time the coil makes a half turn. Because the electric current changes direction, it is an alternating current. • The energy that generators convert into electrical energy comes from different sources such as fossil fuels and nuc ...
Magnetic Force Exerted on a Current
... 3.2 You wonder if you could support your clothesline by running an electric current through it while it resides in the 5 x 10-5 T magnetic field due to the Earth. We’ll assume that you are in Costa Rica near the equator, where the field is parallel to the Earth’s surface. The line is to be 10 m long ...
... 3.2 You wonder if you could support your clothesline by running an electric current through it while it resides in the 5 x 10-5 T magnetic field due to the Earth. We’ll assume that you are in Costa Rica near the equator, where the field is parallel to the Earth’s surface. The line is to be 10 m long ...
A rail gun uses electromagnetic forces to accelerate a projectile to
... mechanism of acceleration is relatively simple and can be illustrated in the following example. A metal rod of mass 50.0 g and electrical resistance 0.100 Ω rests on parallel horizontal rails that have negligible electric resistance. The rails are a distance L = 10.0 cm apart. The rails are also con ...
... mechanism of acceleration is relatively simple and can be illustrated in the following example. A metal rod of mass 50.0 g and electrical resistance 0.100 Ω rests on parallel horizontal rails that have negligible electric resistance. The rails are a distance L = 10.0 cm apart. The rails are also con ...
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. It was discovered by Dutch physicist Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.The electrical resistivity of a metallic conductor decreases gradually as temperature is lowered. In ordinary conductors, such as copper or silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of a normal conductor shows some resistance. In a superconductor, the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing through a loop of superconducting wire can persist indefinitely with no power source.In 1986, it was discovered that some cuprate-perovskite ceramic materials have a critical temperature above 90 K (−183 °C). Such a high transition temperature is theoretically impossible for a conventional superconductor, leading the materials to be termed high-temperature superconductors. Liquid nitrogen boils at 77 K, and superconduction at higher temperatures than this facilitates many experiments and applications that are less practical at lower temperatures.