Question

Coil of 800 turns of effective area $0.05m^2$ is kept perpendicular to a magnetic field of magnitude $5\times {10}^{-5}T$. When the plane of the coil is rotated by $90°$around any of its coplanar axis in $0.1s$, the emf induced in the coil will be

• A. $2V$
• B. $0.2V$
• C. $2\times {10}^{-3}V$
• D. $0.02V$

Answer 1

The correct option is D $0.02V$

Given
$N=800,A=0.05m^2,B=5\times {10}^{-5}T\Delta t=0.1se=-\frac{\left(}{{\Phi }_f-{\Phi }_i}=-\frac{\left(}{NBA\cos \left({90}^0\right)-NBA\cos \left(0^0\right)}=-\frac{\left(}{0-NBA}=\frac{800\times 5\times {10}^{-5}\times 5\times {10}^{-2}}{0.1}=0.02V$