Electromagnetic Induction - Result Question 1
1. A 800 turn coil of effective area $0.05 m^{2}$ is kept perpendicular to a magnetic field $510^{-5}$ $T$. When the plane of the coil is rotated by $90^{\circ}$ around any of its coplanar axis in $0.1 s$, the emf induced in the coil will be :
(a) $2 V$
(b) $0.2 V$
(c) $2 \times 10^{-3} V$
(d) $0.02 V$
[2019]
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Solution:
- (d) Given :
Magnetic field $B=5 \times 10^{-5} T$
Number of turns in coil $N=800$
Area of coil A $=0.05 m^{2}$
Time taken to rotate $=\Delta t=0.1 s$
Initial angle $\theta_1=0^{\circ}$
Final angle $\theta_2=90^{\circ}$
Change in magnetic flux $\Delta \phi$
$=NBA \cos 90^{\circ}-BA \cos 0^{\circ}$
$=-NBA$
$=-800 \times 5 \times 10^{-5} \times 0.05$
$=-2 \times 10^{-2}$ weber
$ \theta=-\frac{\Delta \phi}{\Delta t}=\frac{-(-) 2 \times 10^{-3} Wb}{0.1 s}=0.02 V $
