Three capacitors each of capacitance 9 pF are connected in series.
(a) What is the total capacitance of the combination?
(b) What is the potential difference across each capacitor if the combination is connected to a 120 V supply?
Three capacitors each of capacitance 9 pF are connected in series.
(a) What is the total capacitance of the combination?
(b) What is the potential difference across each capacitor if the combination is connected to a 120 V supply?
Solution and Explanation
(a) Capacitance of each of the three capacitors, C = 9 pF Equivalent capacitance (Ceq) of the combination of the capacitors is given by the relation, \(\frac{1}{Ceq}=\frac{1}{C}+\frac{1}{C}+\frac{1}{C}=\frac{3}{C}=\frac{3}{9}=\frac{1}{3 }=\frac{1}{C_eq}=\frac{1}{3} c_eq=3pF\)
Therefore, total capacitance of the combination is 3 pF.
(b) Supply voltage, V = 100 V Potential difference (V1) across each capacitor is equal to one-third of the supply voltage.
\(V1=\frac{V}{3} =\frac{120}{3} =40 V\)
Therefore, the potential difference across each capacitor is 40 V.
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Concepts Used:
Combination of Capacitors
The total capacitance of this equivalent single capacitor depends both on the individual capacitors and how they are connected. There are two simple and common types of connections, called series and parallel, for which we can easily calculate the total capacitance.
Read Also: Combination of Capacitors
Series capacitors
When one terminal of a capacitor is connected to the terminal of another capacitors , called series combination of capacitors.
Capacitors in Parallel
Capacitors can be connected in two types which are in series and in parallel. If capacitors are connected one after the other in the form of a chain then it is in series. In series, the capacitance is less.
When the capacitors are connected between two common points they are called to be connected in parallel.
When the plates are connected in parallel the size of the plates gets doubled, because of that the capacitance is doubled. So in a parallel combination of capacitors, we get more capacitance.
Read More: Types of Capacitors