Question

Seven capacitors, each of capacitance $2\mu F$, are to be connected in a configuration to obtain an effective capacitance of $\left(\frac{6}{13}\right)\mu F$. Which of the combinations, shown in figure below, will achieve the desired value ?

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

As required, equivalent capacitance should be,

$C_{eq}=\frac{6}{13}\mu F$

So, three capacitors must be in parallel and four must be in series with it.

$\frac{1}{C_{eq}}=\left[\frac{1}{3C}\right]+[\frac{1}{C}+\frac{1}{C}+\frac{1}{C}+\frac{1}{C}]$

$C_{eq}=\frac{3C}{13}=\frac{6}{13}\mu F[\because C=2\mu F]$

So desired combination will be as below:


Hence, $\left(B\right)$ is the correct answer.