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What is the capacitance of this circuit if S is closed? AFAICS, Rules for capacitors in series or parallel can only help to simplify the problem down to

A -- |      |------|--- B

, but this weird parallelism with nothing for the third capacitor is what confuses me.

  • 1
    \$\begingroup\$ C5 and C4 in parallel, and are in series with C1 and C3. (C2 and C6 are shorted, so do nothing) \$\endgroup\$
    – Icy
    Nov 6 '15 at 10:10
  • \$\begingroup\$ As @Icy says/implies, C2 and C6 can have no current through them because they are shorted out. Throw 'em away and what are you left with. \$\endgroup\$
    – Andy aka
    Nov 6 '15 at 10:13
  • \$\begingroup\$ @Icy "(C2 and C6 are shorted, so do nothing)" That's what I anticipated! Can you make that an answer? \$\endgroup\$
    – Columbo
    Nov 6 '15 at 10:13

With Switch S1 closed, circuit reduces to:


simulate this circuit – Schematic created using CircuitLab


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