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 120V supply.

Explanation

(a) Capacitance of each of the three capacitors , C=9 pF
equivalent capacitance (C) of the combination of the capacitors is given by the relation,
`1/(C')=1/C+1/C+1/C`
`=1/9+1/9+1/9=3/9=1/3`
`:. C'=3mu F `
Therefore, total capacitance of the combination is `3muF`
(b) supply voltage, V=100V
potential difference (V) across each capacitor is equal to one-third of the supply voltage.
`:. V'=V/3=120/3=40 V`
therefore, the potential difference across each capacitor is 40 V.