Problem 3.172

A circuit consists of a source of a constant emf \(\mathscr{E}\) and a resist ance \(R\) and a capacitor with capacitance \(C\) connected in series. The internal resistance of the source is negligible. At a moment \(t=0\) the capacitance of the capacitor is abruptly decreased \(\eta\) -fold. Find the current flowing through the circuit as a function of time \(t\).