(d)

Equivalent circuit

 

 

        Hence, no charge will flow through 20 mF

 

        C₁ and C₂ are in series, also C₃ and C₄ are in series.

Hence, C'' = 3 mF, C" = 3 mF

C'' and C" are in parallel.

Hence net capacitance = C'' + C" = 3 + 3 = 6 mF

Dear Student,
Please find below the solution to your problem.


Equivalent circuit


Hence
C1/C3 = C2/C4
Hence, no charge will flow through 20 mF

C1 and C2 are in series, also C3 and C4 are in series.
Hence, C'' = 3 mF, C" = 3 mF
C'' and C" are in parallel.
Hence net capacitance = C'' + C" = 3 + 3 = 6 mF

Thanks and Regards