Class 12 Physics, CBSE and UP Board, Electrostatic Potential and Capacitance,Chapter-2 Exercise 2.6, NCERT Solutions for Class 12 Physics
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?
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(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,
1/Ceq =1/C + 1/C + 1/C = 3/C = 3/9 = 1/3
=> 1/Ceq = 1/3 => Ceq = 3 pF
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.
Therefore V1=V/3=120/3=40V
Therefore, the potential difference across each capacitor is 40 V.