CBSE 2026 · Region 3 · Set 2 · Q7 · 1 mark

A metallic rod of $\displaystyle 1$ m length is rotated with a frequency of $\displaystyle 40$ rev/s, with one end hinged at the centre and the other end at the circumference of a circular metallic ring of radius $\displaystyle 1$ m , about an axis passing through the centre and perpendicular to the plane of the ring. A constant and uniform magnetic field of $\displaystyle 0 \cdot 5 \mathrm{~T}$ parallel to the axis is present in the region. The value of emf induced between the centre and the metallic ring is close to :

(A)

$\displaystyle 20$ V

(B)

$\displaystyle 32$ V

(C)

$\displaystyle 40$ V

(D)

$\displaystyle 63$ V

CBSE Class 12 Physics past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.