Sol. Given arrangement of capacitors is symmetric about mid-point of arm 3-6. If the arrangement is rotated through 180º about this point, given arrangement is obtained again. Let a battery of emf V be connected across terminals 1 and 4 of the arrangement. Then, in steady state, charges on various capacitors will be as shown in Fig.

Applying Kirchhoff's voltage law on mesh 1 – 2 – 6 – 1,

+ – = 0

or q 1 = (q 2 + q 3 ) ….. (1)

For mesh 2 – 3 – 6 – 2,

– – = 0 or q 1 = (2q 2 – 4q 3 ).. (2)

From equations (1) and (2),

q 2 = 5q 3 and q 1 = 6q 3

Now applying Kirchhoff's voltage law on mesh 1 – 6 – 5 – 4 – V – 1,

+ + – V = 0

Substituting q 1 = 6q 3 and

q 2 = 5q 3 , q 3 = CV.

But Charge drawn by the arrangement from battery is

q = (q 1 + q 2 ) = 11q 3 = CV

∴ Equivalent capacitance = = = 11µF