Transient currents in insulators
Dielectric - Theoretical basis

Let's place a plate of solid insulator of thickness d between two metal electrodes and apply a constant potential differenceV₀ to this system constituting a capacitor.

First, a displacement current appears, which may be initially intense, but decays exponentially with a generally fast time constant. This time constant is the product of the sample capacitance and the circuit resistance, possibly including the sample resistance.

• If we assume that this insulator is devoid of any conductivity, a normal charging current i₁ flows through the circuit and decreases with time. This current may continue to decrease for a very long time before stabilizing or cancelling out if conductivity is zero.

  In steady-state operation, the...