4. Transient currents in insulators

4.1 General

Let's place a plate of solid insulator of thickness d between two metal electrodes and apply a constant potential differenceV ₀ 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 i ₁ flows through the circuit and decreases with time. This current may continue to decrease for...