What is the phenomenon in which a current is induced in one coil due to a changing current in a neighbouring coil?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Mutual induction
A changing current in one coil changes the magnetic flux through a neighbouring coil and induces an emf, and so a current, in it. This is mutual induction. The constant \( M_{12} \) in \( \varepsilon_1=-M_{12}\,dI_2/dt \) is the mutual inductance of the pair.
NCERT (2026-27):
Summary – “6. A changing current in a coil (coil 2) can induce an emf in a nearby coil (coil 1). This relation is given by,
\( \displaystyle \varepsilon_1=-M_{12}\frac{dI_2}{dt} \)
The quantity M12 is called mutual inductance of coil 1 with respect to coil 2.”