Question

The series combination of 5 F and 20 F capacitors is connected in parallel to 4 F capacitor. What is the energy stored in the combination of capacitors?

Answer 1

The net capacitance of system

$$C_{net}=\frac{C_1C_2}{C_1+C_2}+C_3$$

$$C_{net}=\frac{5\times20}{5+20}+4=8\rm \: F$$

The energy stored in the combination of capacitors

$$W=\frac{C_{net}V^2}{2}$$