Question

A magnetic field of $2\times 10^{-2}$T acts at right angles to a coil of area 100 $cm^2$, with 50 turns. The average e.m.f. induced in the coil is 0.1 V, when it is removed from the field in t sec. The value of t is

• A. 10 s
• B. 0.1 s
• C. 0.01 s
• D. 1 s

Answer 1

Answer: (B)

0.1 s

Answer 2

$\in=\frac{-(\phi_2-\phi_1)}{t}=\frac{-(0-NBA)}{t}=\frac{NBA}{t}$
$t=\frac{NBA}{\in}=\frac{50\times2\times10^{-2}\times10^{-2}}{0.1}=0.1 \, s$