V

vacuum tube A tube which has been exhausted to a high degree of vacuum so that the amount of gas present in the envelope is too small to have any effect on the electrical characteristics. The tube may be sealed or continuously pumped. Currents in a vacuum tube are carried by electrons not ions.

valence The force which binds atoms together to form a molecule.

valence band In an energy-level diagram the range of energies corresponding to states which can be occupied by the valence electrons binding the atoms together.

valence electrons Electrons occupying the outermost orbits of an atom and which are shared when atoms combine to form molecules. See covalent bonds.

value (1) The numerical level of the primary property of a passive component, ...

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