Question

A 10 ohm resistance coil has 1000 turns it is placed in a magnetic field of magnetic induction 5×10^-4 tesla in 0.1 second. If area of cross section is one square metre, then the average induced emf is

Answer 1

number of turns , N = 1000

magnetic field of magnetic induction , B = 5 × 10^-4 T

time , t = 0.1

cross sectional area, A = 1 m²
according to Faraday's law of magnetic induction.
induced emf is negative of rate of change of magnetic flux.
e.g., $\mathbb{E}=-\frac{d\phi}{dt}$
if N number of turns of coil, $\mathbb{E}=-N\frac{d\phi}{dt}$
we know, induced emf = -N × BA/t

= - 1000 × 5 × 10^-4 × 1/0.1

= -5 volt

hence, induced emf = - 5 volt