Question

Obtain the equivalent capacitance of the network in Fig. 2.35. For a 300 V supply, determine the charge and voltage across each capacitor.

Answer 1

Capacitance of capacitor C₁ is 100 pF.

Capacitance of capacitor C₂ is 200 pF.

Capacitance of capacitor C₃ is 200 pF.

Capacitance of capacitor C₄ is 100 pF.

Supply potential, V = 300 V

Capacitors C₂ and C₃ are connected in series. Let their equivalent capacitance be

Capacitors C₁ and C’ are in parallel. Let their equivalent capacitance be

are connected in series. Let their equivalent capacitance be C.

Hence, the equivalent capacitance of the circuit is

Potential difference across =

Potential difference across C₄ = V₄

Charge on

Q₄= CV

Hence, potential difference, V₁, across C₁ is 100 V.

Charge on C₁ is given by,

C₂ and C₃ having same capacitances have a potential difference of 100 V together. Since C₂ and C₃ are in series, the potential difference across C₂ and C₃ is given by,

V₂ = V₃ = 50 V

Therefore, charge on C₂ is given by,

And charge on C_{3 ­}is given by,

Hence, the equivalent capacitance of the given circuit is