Question

The equivalent capacitance across $\text{AB}$ is

• A. $8\mu \text{F}$
• B. $12\mu \text{F}$
• C. $4\mu \text{F}$
• D. $24\mu \text{F}$

Answer 1

The correct option is C $4\mu \text{F}$

Given circuit:

Since, capacitors $6\mu \text{F}$ and $12\mu \text{F}$ are in series and thies equivalent capacitance $\frac{6\times 12}{6+12}=4\mu \text{F}$ is in parallel with $4\mu \text{F}$ capacitor. Redrawing the circuit,


Since, both the $8\mu \text{F}$ capacitors are in series so, their equivalent capacitance, $\frac{8\times 8}{8+8}=4\mu \text{F}$.


Finally,
So, the equivalent capacitance, $(C_{eq}{)}_{AB}=4\mu F$

Hence, option (c) is correct answer.

Why this question : This question is aimed at recalling the approch of succesive reduction of the electrical circuits. Note : This method will be very helpful in current electricity as well.