Class 12th Physics 2017 Set3 Delhi Board Paper Solution
Two identical capacitors of 12 pF each are connected in series across a battery of 50 V. How much electrostatic energy is stored in the combination? If these were connected in parallel across the same battery, how much energy will be stored in the combination now?
Also find the charge drawn from the battery in each case.
In series combination:
1 / Ceq = [1/12 + 1/12] Pf ⇒ Ceq = 6 x 10-12 F
Electrostatic energy stored is ½ Ceq V2 = 1/2 x 6 x 10-12 x 502 = 7.5 x 10-9J
Charge drawn from the battery = Q = 6 x 10-12 x 50 = 3 x 10-10C
In Parallel Ceq = C1 +C2 = 12+12 = 24pF
Energy Stored = ½ Ceq V2 = 1/2 x 24 x 10-12 x 502 = 3 x 10-8J
Charge drawned from battery Q = Ceq V = 24 x 10-12 x 50 = 1.2 x 10-9C.
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