RC circuit

A RC circuit consists of a resistor R and a capacitor C in series. It has the time constant t calculated with

When a voltage is applied to the circuit, the charging current decreases from I0=U0/R exponentially with t towards 0. C will be charged to about 63% after t, and fully charged after about 5*t. When the voltage source is removed with C fully charged and the circuit short circuited, voltage at C drops exponentially with t from U0 towards 0. C will be decharged to about 37% after t, and fully decharged after about 5*t.