Question 7

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

(a) Capacitances of the given capacitors are

C_{1 }= 2 pF,

C_{2} = 3 pF,

C_{3} = 4 pF,

For the parallel combination of the capacitors, equivalent capacitoris *C'* given by the algebraic sum,

*C'*=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 … (i)

For C = 2 pF,

Charge=* VC *= 100 x 2 = 200 pC = 2 x 10^{-10} C

For C = 3 pF,

Charge =* VC* = 100 x 3 = 300 pC = 3 x 10^{-10} C

For C = 4 pF

Charge = *VC *= 100 x 4 = 400 pC = 4 x 10^{-10} C

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- NCERT Chapter

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