A circuit consists of an ideal battery of potential difference \(V_0\), three identical resistors each of resistance \(R\), and an open switch \(S\), as shown in the diagram. Resistors \(R_1\) and \(R_2\) are connected in series across the battery, while resistor \(R_3\) and switch \(S\) form a branch connected in parallel across \(R_2\). What is the ratio \(P_f / P_i\) of the rate of energy dissipation in resistor \(R_1\) after switch \(S\) is closed to the rate of energy dissipation in resistor \(R_1\) before switch \(S\) is closed?