Question

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.

Answer 1

(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=9 pF

Therefore, total capacitance of the combination is 9 pF.

(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

For C = 2 pF, charge = VC = 100 × 2 = 200 pC = 2 × 10–10 C

For C = 3 pF, charge = VC = 100 × 3 = 300 pC = 3 × 10–10 C

For C = 4 pF, charge = VC = 100 × 4 = 400 pC = 4 × 10–10 C