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where is the length of the conductor, measured in metres [m], A is the cross-section area of the conductor measured in square metres [m 2], σ is the electrical conductivity measured in siemens per meter (S·m −1), and ρ is the electrical resistivity (also called specific electrical resistance) of the material, measured in ohm-metres (Ω·m ...
The atoms of the insulator have tightly bound electrons which cannot readily move. Other materials—semiconductors and conductors—conduct electric current more easily. The property that distinguishes an insulator is its resistivity; insulators have higher resistivity than semiconductors or conductors. The most common examples are non-metals.
Most metals have electrical resistance. In simpler models (non quantum mechanical models) this can be explained by replacing electrons and the crystal lattice by a wave-like structure. When the electron wave travels through the lattice, the waves interfere, which causes resistance. The more regular the lattice is, the less disturbance happens ...
Diamond is the best natural conductor of heat; it even feels cold to the touch. Its thermal conductivity (2,200 W/m•K) is five times greater than the most conductive metal (Ag at 429); 300 times higher than the least conductive metal (Pu at 6.74); and nearly 4,000 times that of water (0.58) and 100,000 times that of air (0.0224). This high ...
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 ...
Metals and other solid materials expand upon heating and contract upon cooling. This is an undesirable occurrence in electrical systems. Copper has a low coefficient of thermal expansion for an electrical conducting material. Aluminium, an alternate common conductor, expands nearly one third more than copper under increasing temperatures.
This transition is known to exist in various systems: mercury metal vapor-liquid, metal NH 3 solutions, transition metal chalcogenides and transition metal oxides. [15] In the case of transition metal oxides, the material typically switches from being a good electrical insulator to a good electrical conductor.
In electrostatics, a perfect conductor is an idealized model for real conducting materials. The defining property of a perfect conductor is that static electric field and the charge density both vanish in its interior. If the conductor has excess charge, it accumulates as an infinitesimally thin layer of surface charge. An external electric ...