Question

The coil of area $0.1\, m ^{2}$ has $500$ turns. After placing the coil in a magnetic field of strength $4 \times 10^{-4} Wb / m ^{2}$, if it is rotated through $90^{\circ}$ in $0.1\, s$, the average emf induced in the coil is

• A. 0.012 V
• B. 0.05 V
• C. 0.1 V
• D. 0.2 V

Answer 1

Answer: (D)

$e=\frac{-N B A\left(\cos \theta_{2}-\cos \theta_{1}\right)}{\Delta t}$
$=-\frac{500 \times 4 \times 10^{-4} \times 0.1\left(\cos 90^{\circ}-\cos 0^{\circ}\right)}{0.1}$
$=0.2\, V$