A circuit consists of a source of a constant emf and a resistance R and a capacitor

Question:

A circuit consists of a source of a constant emf ε and a resistance 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 xl-fold. Find the current flowing through the circuit as a function of time t.