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The ampacity of a conductor, that is, the amount of current it can carry, is related to its electrical resistance: a lower-resistance conductor can carry a larger value of current. The resistance, in turn, is determined by the material the conductor is made from (as described above) and the conductor's size.
In general, electrical resistivity of metals increases with temperature. Electron–phonon interactions can play a key role. At high temperatures, the resistance of a metal increases linearly with temperature. As the temperature of a metal is reduced, the temperature dependence of resistivity follows a power law function of temperature.
Substances in which electricity can flow are called conductors. A piece of conducting material of a particular resistance meant for use in a circuit is called a resistor. Conductors are made of high-conductivity materials such as metals, in particular copper and aluminium. Resistors, on the other hand, are made of a wide variety of materials ...
The chemical elements can be broadly divided into metals, metalloids, and nonmetals according to their shared physical and chemical properties.All elemental metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form alloys with other metallic elements; and have at least one basic oxide.
Bad contacts are the cause of failure or poor performance in a wide variety of electrical devices. For example, corroded jumper cable clamps can frustrate attempts to start a vehicle that has a low battery. Dirty or corroded contacts on a fuse or its holder can give the false impression that the fuse is blown.
Conductors, typically in the form of wires, may be used to transfer electrical energy or signals using an alternating current flowing through that conductor. The charge carriers constituting that current, usually electrons , are driven by an electric field due to the source of electrical energy.
Normally, metal electrical equipment cases are bonded to ground to prevent a shock hazard if energized conductors accidentally contact the case. Where this bonding is not provided or has failed, a severe hazard of electric shock or electrocution is presented when circuit conductors contact the case.
The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C (212 and 302 °F). [9] [10] Above 210 °C (410 °F), the metal becomes brittle again and can be pulverized by beating. [15] Zinc is a fair conductor of electricity. [9]