Q. Three capacitors of capacitance 1$\mu F,\ 2\mu F\ and\ 3\mu F$ are connected in series and a potential difference of 11 V is applied across the combination. Then, the potential difference across the plate of 1$\mu F$ capacitor is

A) 2 V
B) 4 V
C) 1 V
D) 6 V
Explanation

(d) Let potential difference between the plates of the capacitors $C_{1},C_{2}\ and\ C_{3}\ be\ V_{1},\ V_{2}\ and\ V_{3}and\ q$ be the charge.
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Then, $V = \frac{q}{C_{1}},\ V_{2} = \frac{q}{C_{2}},\ V_{3} = \frac{q}{C_{3}}$
The total potential difference $V = 11$volt
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ V = V_{1} + V_{2} + V_{3}$
$\Rightarrow \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ V = \frac{q}{C_{1}} + \frac{q}{C_{2}} + \frac{q}{C_{3}} = 11$
Given, $C_{1} = 1\mu F,\ C_{2} = 2\mu F,C_{3} = 3\mu F$
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 11 = q\left( \frac{1}{1} + \frac{1}{2} + \frac{1}{3} \right)$
$\Rightarrow \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 11 = \frac{11q}{6}$
$\Rightarrow \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ q = 6\mu c$
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ V_{1}\ = \ \frac{q}{C_{1}} = \frac{6}{1} = 6$ V

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.