Question

Given four capacitors each of capacity 12$\mu$F. To get a capacity of 9$\mu$F, what combination can be used:

• A. All in series
• B. All in parallel
• C. 3 in parallel and 1 series with them
• D. 2 in parallel and 2 in series

Answer 1

The correct option is C 3 in parallel and 1 series with them

Formula for equivalent capacitance in parallel

$C_{eq}=C_1+C_2$

Formula for equivalent capacitance in series

$\frac{1}{C_{eq}}=\frac{1}{C_1}+\frac{1}{C_2}$

So, For 3 capacitance $\left(9\mu Feach\right)$ in parallel and 1 series ,the equivalent capacitance =

$\frac{1}{C_{eq}}=\frac{1}{36}+\frac{1}{12}$

$\Rightarrow C_{eq}=\frac{36\times 12}{36+12}$

$\Rightarrow C_{eq}=9\mu F$

Therefore, C is correct option.