In an inductive circuit, the current falls from 7.5 A to 1.5 A in 0.15 s. It induces emf of 220 V in the inductive coil. The inductance of the circuit is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 5.5 H
A changing current in a coil induces an emf in the same coil through its self-inductance. In magnitude, the emf is set by the rate of change of current:
\( \displaystyle \varepsilon = L\,\frac{|\Delta I|}{\Delta t} \;\Rightarrow\; L = \frac{\varepsilon\,\Delta t}{|\Delta I|} \)
\( \varepsilon = 220\,\mathrm{V} \)
\( |\Delta I| = 7.5 - 1.5 = 6.0\,\mathrm{A} \)
\( \Delta t = 0.15\,\mathrm{s} \)
\( \displaystyle L = \frac{220 \times 0.15}{6.0} = \frac{33}{6.0} = 5.5\,\mathrm{H} \)
Note: NTA picked this question from an NCERT (2026-27) exercise and changed the figures. Do not ignore NCERT while practising numericals.
NCERT (2026-27):
Exercises – …
