Question

A flat coil, C, of n turns, area A and resisitance R is placed in a uniform magnetic field of magnitude B. The plane of the coil is initially perpendicular to B. If the coil is rotated by an angle about the axis XY, charge of amount Q flows through it. if the coil rotates about XY with a constant angular velocity $\omega$, the emf induced in it.

• A. is zero
• B. changes nonlinearly with time
• C. has a constant value $=$ BAn$\omega$
• D. has a maximum value $=$ BAn$\omega$

Answer 1

Answer: (A), (D)

The correct options are
A is zero
D has a maximum value $=$ BAn$\omega$

Flux $=n\overrightarrow{A}.\overrightarrow{B}=nABcos\theta$

emf $=$ rate of change of flux $=\frac{dflux}{dt}=-nABsin\theta \frac{d\theta }{dt}=-nAB\omega sin\theta$

$=<-nAB\omega sin\theta >=-nAB\omega =0$

max emf $=nAB\omega$