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Three pure inductors, each of 3 H, are connected as shown in the figure. The equivalent inductance of this connection between points A and B is ......

Asked in RS Academy GUJCET booklet · Coil geometry, cores and combinations

• (1) 1 H
• (2) 2 H
• (3) 3 H
• (4) 9 H

Step-by-step solution

Why the other options are wrong

• (2) Comes from putting two coils in series and that pair in parallel with the third: (6×3)/(6+3)=2 H. In the figure every coil runs straight from the A junction to the B junction.
• (3) Treats the middle coil, the one in line with A and B, as the only path. The top and bottom coils join the same two junctions, so they share the current.
• (4) Adds all three as if in series: 3+3+3=9 H. Series would need the current to pass through the coils one after another, which it does not here.

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