From the circuit given below, the capacitance between the terminals A and B is μ F. Take C₁=C₂=C₃=1 μ F and C₄=2 μ F. A connects through C₁ to a node M, M connects through C₂ to a node N, and N connects through C₃ to B; a plain wire joins A directly to N, and C₄ is joined between M and B.

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Accepted Answer

(1) 2. The plain wire makes A and N the same node, so redraw the circuit with only three nodes: A(=N), M and B. C₁ runs from A to M and C₂ runs from M to N=A, so they are in PARALLEL between A and M: C_AM=1+1=2 μ F. C₄ runs from M to B: 2 μ F. These two form a path A→ M→ B in series: (2×2)/(2+2)=1 μ F. C₃ runs from N=A straight to B, so it is in parallel with that path: 1+1=2 μ F.

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