Three capacitors of capacitances 2 \mathrm{pF}, 3 \mathrm{pF} and 4 \mathrm{pF} are connected in parallel.
(1) What is the total capacitance of the combination?
(2) Determine the charge on each capacitor if the combination is connected to a 100 \mathrm{~V} supply.
Three capacitors of capacitances 2 \mathrm{pF}, 3 \mathrm{pF} and 4 \mathrm{pF} are connected in parallel.
(1) What is the total capacitance of the combination?
(2) Determine the charge on each capacitor if the combination is connected to a 100 \mathrm{~V} supply.

Solution:

(1) Given, C_{1}=2 p F, C_{2}=3 p F and C_{3}=4 p F.

Equivalent capacitance for the parallel combination is given by \mathrm{C}_{\mathrm{eq}}.

Therefore, \mathrm{C}{\mathrm{eq}}=\mathrm{C}{1}+\mathrm{C}{2}+\mathrm{C}{3}=2+3+4=9 \mathrm{pF}

Hence, the total capacitance of the combination is 9 \mathrm{pF}.

(2) Supply voltage, V=100 \mathrm{~V}

The three capacitors have the same voltage as one another, V=100 v

We know that, q=V C

where, q= charge : C= capacitance of the capacitor
V= potential difference

For capacitance, c=2 \mathrm{pF}

q=100 \times 2=200 \mathrm{pC}=2 \times 10^{-10} \mathrm{C}

for capacitance, c=3 \mathrm{pF}

q=100 \times 3=300 \mathrm{pC}=3 \times 10^{-10} \mathrm{C}

for capacitance, c=4 \mathrm{pF}

q=100 \times 4=400 \mathrm{pC}=4 \times 10^{-10} \mathrm{C}