Question

Question 2.6: Three capacitors each of capacitance 9 pF are connected in series. (a) What is the total capacitance of the combination? (b) What is the potential difference across each capacitor if the combination is connected to a 120 V supply?

Class 12 - Physics - Electrostatic Potential And Capacitance Electrostatic Potential And Capacitance Page-87

Answer 1

If capacitors are connected in series then equivalent capacitance of capacitors is given by 1/Ceq = 1/C₁ + 1/C₂ + 1/C₃ + 1/C₄ + .......

Here, C₁ = C₂ = C₃ = 9pF
so, 1/Ceq = 1/C₁ + 1/C₂ + 1/C₃
= 1/9 + 1/9 + 1/9
= 3/9
= 1/3
Ceq = 3pF

(b) Net charge stored in combination of capacitors is Q = CeqV
= 3pF × 120V
= 3 × 10⁻¹² × 120
= 360 × 10⁻¹² C = 360pC

Now, potential difference across each capacitor is
V₁ = Q/C₁ = 360pC/9pF = 40V

Answer 2

Answer:

a) 3/9 pf

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