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The current in a circuit falls from 5 A to 0 A in 0.1 s. If an average emf of 200 V is induced, the self-inductance of the circuit would be ____ H.

Asked in GSEB Board March 2022 · Self-inductance and self-induced EMF

• (1) 3
• (2) 2
• (3) 1
• (4) 4

Step-by-step solution

Why the other options are wrong

• (1) No single slip produces 3 H. Sanity check: L=(ε Δ t)/(|Δ I|)=(200×0.1)/5 fixes it at 4 H.
• (2) No single slip produces 2 H; it is half the right value. Sanity check: the current falls at 5/(0.1)=50 A s⁻¹, and (200)/(50)=4 H.
• (3) No single slip produces 1 H; it is a quarter of the right value. Sanity check: 1 H falling at 50 A s⁻¹ would induce only 50 V, not 200 V.

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