Question

Three capacitors of capacitance C₁ = 3 μf C₂ = 6 μf and C₃ = 10 μf are connected to a 10 V battery as shown in Figure 3 below :

Calculate:

(a) Equivalent capacitance.

(b) Electrostatic potential energy stored in the system.

Answer 1

3 μf and 6 μf capacitors are connected in series, therefore, their net capacitance

C_s = \(\frac{3\times6}{3\times6}\) = \(\frac{18}{9}\) = 2 μf

This is connected in parallel to the 10  μf capacitor, hence net capacitance of the circuit.

C_p = 2 + 10 = 12 μf

(b) U = \(\frac{1}{2}CV^2\) = \(\frac{1}{2}\times12\times10^{-6}\times(10)^2\)

= 6 x 10^-4 J