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A dipole is characterised by its dipole moment, a vector quantity shown in the figure as the blue arrow labeled M. It is the relationship between the electric field and the dipole moment that gives rise to the behaviour of the dielectric. (Note that the dipole moment points in the same direction as the electric field in the figure.
According to Gauss’s law, a conductor at equilibrium carrying an applied current has no charge on its interior.Instead, the entirety of the charge of the conductor resides on the surface, and can be expressed by the equation: = where E is the electric field caused by the charge on the conductor and is the permittivity of the free space.
The monopole antenna is essentially one half of the half-wave dipole, a single 1 / 4 wavelength element with the other side connected to ground or an equivalent ground plane (or counterpoise). Monopoles, which are one-half the size of a dipole, are common for long-wavelength radio signals where a dipole would be impractically large.
A semiconductor diode, the most commonly used type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. [5] It has an exponential current–voltage characteristic. Semiconductor diodes were the first semiconductor electronic devices.
Electrical Engineering: Problems and Solutions. Dearborn Trade Publishing. ISBN 978-1-4195-2131-7. Karalis, Edward (18 September 2003). 350 Solved Electrical Engineering Problems. Dearborn Trade Publishing. ISBN 978-0-7931-8511-5. Krawczyk, Andrzej; Wiak, S. (1 January 2002). Electromagnetic Fields in Electrical Engineering. IOS Press.
Eddy currents are minimized in these devices by selecting magnetic core materials that have low electrical conductivity (e.g., ferrites or iron powder mixed with resin) or by using thin sheets of magnetic material, known as laminations. Electrons cannot cross the insulating gap between the laminations and so are unable to circulate on wide arcs.
Electric fields are important in many areas of physics, and are exploited in electrical technology. For example, in atomic physics and chemistry , the interaction in the electric field between the atomic nucleus and electrons is the force that holds these particles together in atoms.
Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The electric current produces a magnetic field around the conductor. The magnetic field strength depends on the magnitude of the electric current, and therefore follows any changes in the magnitude of the current.