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MHT CET202523 Apr 2025Evening ShiftPhysicsElectromagnetic InductionActual

Two identical coils of inductance L joined in series are placed very close to each other such that the winding direction of one coil is exactly opposite to that of the other. The net inductance is

Options

  1. AL 2
  2. B2 L
  3. Czero
  4. DL

Correct answer

C. zero

Step-by-step solution

Net inductance for series-connected coils is L_ net = L₁ + L₂ 2M , where the sign depends on magnetic field alignment. With identical coils, L₁ = L₂ = L . Opposite winding directions produce opposing magnetic fields, indicating subtractive coupling: L_ net = L + L - 2M . Identical coils in close proximity with opposing windings achieve perfect coupling ( k=1 ), so M = L . L_ net = 2L - 2L = 0 The net inductance is zero.

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