Question

A coil has 2000 turns and area of $70cm^{2}$. The magnetic field perpendicular to the plane of the coil is $0.3Wb/m^{2}$and takes 0.1sec to rotate through $180^{o}$. The value of the induced e.m.f. will be

• A. $8.4V$
• B. $84V$
• C. $42V$
• D. $4.2V$

Answer 1

Answer: (B)

$84V$

Answer 2

$e = - \frac{NBA(\cos\theta_{2} - \cos\theta_{1})}{\Delta t}$

$= - 2000 \times 0.3 \times 70 \times 10^{- 4}\frac{(\cos 180 - \cos 0)}{0.1}$

$\Rightarrow e = 84\mspace{6mu} V$