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Besides the capacitance, an important thing to know about a
capacitor is its maximum working voltage. In Sec. 2.3 we visualised
insulators as substances in which the electrons are unable to drift
through the material in large numbers under the influence of an
electric field but instead they 'strain at the leash', being slightly
displaced from their normal positions in the atoms. If the intensity
of electric field is increased beyond a certain limit the elastic leashes
tethering the electrons snap under the strain, and the freed electrons
rush uncontrollably to the positive plate, just as if the dielectric were
a good conductor. It has, i ...