Class 12 Physics, CBSE and UP Board, Electrostatic Potential and Capacitance, Chapter-2 Exercise 2.7, NCERT Solutions for Class 12 Physics
Three capacitors of capacitances 2 pF, 3 pF and 4 pF are connected in parallel. (a) What is the total capacitance of the combination? (b) Determine the charge on each capacitor if the combination is connected to a 100 V supply.
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Ans (a).
Capacitances of the given capacitors: C₁ = 2 pF, C2 = 3 pF and C3 = 4 pF
For the parallel combination of the capacitors, equivalent capacitor is given by Ceq the algebraic sum,
Therefore Ceq = C₁+C2 + C3 = 2 + 3+ 4 = 9pF
Therefore, total capacitance of the combination is 9 pF.
Ans (b).
Supply voltage, V = 100 V
The voltage through all the three capacitors is same = V = 100 V
Charge on a capacitor of capacitance C and potential difference V is given by the relation,
q=VC… (i)
For C = 2 pF, charge = VC = 100 x 2 = 200 pC = 2 x lO⁻10 C
For C = 3 pF, charge = VC = 100 x 3 = 300 pC = 3 x lO⁻10 C
For C = 4 pF, charge = VC = 100 x 4 = 400 pC = 4 x 10⁻10 C