How is the axis of rotation of the coil in an ac generator oriented with respect to the magnetic field?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Perpendicular
With the axis of rotation perpendicular to the field, the angle between \( \vec{B} \) and the area vector \( \vec{A} \) runs through every value as the coil turns. So the flux \( BA\cos\theta \) keeps changing between \( +BA \) and \( -BA \). If the axis were parallel to the field, the area vector would always stay perpendicular to \( \vec{B} \). The flux would then stay zero and no emf would be induced.
NCERT (2026-27):
AC Generator – “… The axis of rotation of the coil is perpendicular to the direction of the magnetic field.”