Question

For what value of C equivalent capacitance across AB is independent of number of repeated sections.

• A. $\frac{30}{7}F$
• B. $\frac{15}{7}F$
• C. $\frac{60}{7}F$
• D. $3F$

Answer 1

The correct option is D $3F$

Let equivalent capcitance is $y$ because of some that now
$=\frac{6(3+y)}{9+y}=y$
$9y+y^2=18+6y$
$y^2+3y-18=0$
$y^2+6y-3y-18=0$
$y(y+1)-3(y+6)=0$
$y=+3,-6$
$\therefore y=+3$

So 3F will be answer