Question

A 50 turns circular coil has a radius of$3\mspace{6mu} cm$, it is kept in a magnetic field acting normal to the area of the coil. The magnetic field $B$ increased from 0.10 tesla to 0.35 tesla in 2 milliseconds. The average induced e.m.f. in the coil is

• A. $1.77\mspace{6mu} volts$
• B. $17.7\mspace{6mu} volts$
• C. $177\mspace{6mu} volts$
• D. $0.177\mspace{6mu} volts$

Answer 1

Answer: (B)

$17.7\mspace{6mu} volts$

Answer 2

$e = - \frac{N(B_{2} - B_{1})A\cos\theta}{\Delta t}$

$= - \frac{50(0.35 - 0.10) \times \pi(3 \times 10^{- 2})^{2} \times \cos 0^{o}}{2 \times 10^{- 3}} = 17.7\mspace{6mu} V$.