3. In the network shown above, C1 = 6 UF, C2 = 3 UF, C3 = 4 HF, and C4 = 8 JF. A potential difference Vab is applied between points a and b. After the charges on the capacitors have reached their final values, the voltage across C3 is 40 V. C1 C2 a C3 b C4 What is the value of Vab