Question

All plates are of same area (A). Find effective capacitance between A & B

• A. $\frac{3}{5}\frac{{ϵ}_{0}A}{d}$
• B. $\frac{5}{3}\frac{{ϵ}_{0}A}{d}$
• C. $\frac{4}{3}\frac{{ϵ}_{0}A}{d}$
• D. $4\frac{{ϵ}_{0}A}{d}$

Answer 1

The correct option is B $\frac{5}{3}\frac{{ϵ}_{0}A}{d}$


$(1,6,7)\to$ connected to "+ve"
$(4,5)\to$ connected to "(-ve)"
$(2,3,8)\to$ inter connected.

Since the area and distacne between all the plates are same, they all have the same value of capacitance $C=\frac{{ϵ}_{o}A}{d}$

$C_{78}$ parallel to $C_{12}$ = $2C$
$2C$ is parallel to $C_{12}=\frac{2}{3}C$
$\frac{2}{3}C$ is parallel to $C_{65}=\frac{5}{3}C=\frac{5}{3}\frac{{ϵ}_{o}A}{d}$