Question

Capacitors can be combined to obtain any desired capacitance in an application. 

1. You are given two capacitors of capacitance 20µF each. Draw a diagram to show how you will connect these capacitors to get 40µF capacitance.

2. Two capacitors C₁ and C₂ are connected in series.

(a) Draw a diagram of the above combination.

(b) If C₁ = 4µF, C₂ = 6µF and C₃ = 2.4µF and a potential difference of 100 V is applied across the combination. Calculate the change stored in each capacitor.

Answer 1

1.

2. Two capacitors C₁ and C₂ are connected in series:
(a)

(b) Effective capacitance C₁ anc C₂

\(C_{12}=\frac{C_1C_2}{C_1+C_2}\) = \(\frac{4\times6}{4+6}\) = 2.4µF

Potential difference across C₁₂ = 100V

Charge stored on C₁₂, q₁₂ = C₁₂ × 100

q₁₂ = 2.4 × 10^-6 × 100

q₁₂ = 2.4 × 10^-4 C

Charge on C₁

q₁ = 2.4 × 10^-4C

Charge on C₂

q₂ = 2.4 × 10 ^-4C

Potential difference across C₃ = 100V

Charge on C₃

q₃ = C₃ × 100

q₃ = 2.4 × 10^-6 × 100

q₃ = 2.4 × 10^-4C.