Capacitors of capacities $\mathrm{C}_1, \mathrm{C}_2$ and $\mathrm{C}_3$ are connected in series. If the…

Capacitors of capacities $\mathrm{C}_1, \mathrm{C}_2$ and $\mathrm{C}_3$ are connected in series. If the combination is connected to a supply of ' $\mathrm{V}$ ' volt, then potential difference across capacitor ' $\mathrm{C}_1$ ' is
  1. $\frac{\mathrm{C}_2 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_2}{\mathrm{C}_1 \mathrm{C}_2 \mathrm{~V}}$
  2. $\frac{\mathrm{C}_2 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_2}{\mathrm{C}_1 \mathrm{C}_2 \mathrm{C}_3 \mathrm{~V}}$
  3. $\frac{\mathrm{C}_2 \mathrm{C}_3 \mathrm{~V}}{\mathrm{C}_2 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_2}$
  4. $\frac{\mathrm{C}_1 \mathrm{C}_2 \mathrm{C}_3 \mathrm{~V}}{\mathrm{C}_2 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_2}$

Solution

In series combination, the equivalent capacitance $\mathrm{C}$ is given by $\begin{aligned} & \frac{1}{\mathrm{C}}=\frac{1}{\mathrm{C}_1}+\frac{1}{\mathrm{C}_2}+\frac{1}{\mathrm{C}_3} \\ & \therefore \frac{1}{\mathrm{C}}=\frac{\mathrm{C}_2 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_2}{\mathrm{C}_1 \mathrm{C}_2 \mathrm{C}_3}\end{aligned}$ $\therefore \mathrm{C}=\frac{\mathrm{C}_1 \mathrm{C}_2 \mathrm{C}_3}{\mathrm{C}_2 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_2}$ Charge $\mathrm{Q}$ stored by the combination is given by $\mathrm{Q}=\mathrm{CV}=\frac{\mathrm{C}_1 \mathrm{C}_2 \mathrm{C}_3 \mathrm{~V}}{\mathrm{C}_2 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_3+\mathrm{C}_1 \mathrm{C}_2}$ Charge on each capacitor is same. Hence potential difference across $C_1$ is $V_1=\frac{Q}{C_1}=\frac{C_2 C_3 V}{C_2 C_3+C_1 C_3+C_1 C_2}$

Asked in: MHT CET 2021 (24 Sep Shift 2)

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