A coil of turns and area starts from rest and rotates about a fixed axis in a uniform…

PHYSICS · Single correct · CBSE · Physics · Electromagnetic Induction · Electromagnetic Induction

Problem

A coil of

N

turns and area

A

starts from rest and rotates about a fixed axis in a uniform magnetic field

B

with a constant angular acceleration

\alpha

. The plane of the coil is perpendicular to the field at

t=0

. Which expression gives the instantaneous emf at time

t

? (a)

\varepsilon = N B A\, \alpha t\, \cos\!\left(\tfrac{1}{2}\alpha t^{2}\right)

(b)

\varepsilon = N B A\, \alpha t\, \sin\!\left(\tfrac{1}{2}\alpha t^{2}\right)

(c)

\varepsilon = N B A\, \alpha t\, \sin\!\left(\alpha t^{2}\right)

(d)

\varepsilon = \tfrac{1}{2} N B A\, \alpha t\, \sin\!\left(\tfrac{1}{2}\alpha t^{2}\right)