Capacitor

Four capacitors with capacitances \(C_1=l \propto \mathrm{F}, C_2=1.5 \propto \mathrm{F}, C_3=2.5 \propto \mathrm{F}\) and \(C_4=0.5 \propto \mathrm{F}\) are connected as shown and are connected to a \(30 \mathrm{~V}\) source. The potential difference between points \(a\) and \(b\) is