CBSE Class 12 · 2009 · CapacitanceShort Answer

The equivalent capacitance of the combination between A and B in the given figure is

4 μ F

, where the

20 μ F

capacitor is in series with a capacitor C. (i) Calculate the capacitance of the capacitor C. (ii) Calculate the charge on each capacitor if a 12 V battery is connected across terminals A and B. (iii) What will be the potential drop across each capacitor?

Solution

(i) For the two capacitors in series:

\frac{1}{4} = \frac{1}{20} + \frac{1}{C}

\frac{1}{C} = \frac{1}{4} - \frac{1}{20} = \frac{4}{20}

C = 5 μ F

(ii) The series combination carries the same charge on each:

q = C_{e q} V = 4 \times 1 0^{- 6} \times 12 = 48 μ C

(iii) Voltage across each:

V_{20} = \frac{q}{20 μ F} = 2.4 V, V_{5} = \frac{q}{5 μ F} = 9.6 V

(which sum to 12 V).

CBSE Class 12 Board · 2009 · Subjective

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