Question

A rectangular coil of $300$ turns has an average area of average area of $25\, cm \times 10\, cm .$ The coil rotates with a speed of $50\, cps$ in a uniform magnetic field of strength $4 \times 10^{-2} T$ about an axis perpendicular of the field. The peak value of the induced e.m.f. is (in volt)

• A. $3000\, \pi$
• B. $300\, \pi$
• C. $30\, \pi$
• D. $3\, \pi$

Answer 1

Answer: (C)

Peak value of $emf =e_{0}=\omega N B A=2 \pi \vee N B A$
$=2 \pi \times 50 \times 300 \times 4 \times 10^{-2} \times\left(25 \times 10^{-2} \times 10 \times 10^{-2}\right)=30\, \pi$ volt.