A coil of 500 turns is threaded by a magnetic flux of $7 \times 10^{-5} Wb$. If the flux changes to $3 \times 10^{-5} Wb$ in 0.01 s, what average induced emf is developed in the coil? If resistance offered by the coil is $10 \Omega$, then the flow of average induced current will be:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 2 V, 0.2 A
According to faraday's law of induction,
$ε=-N\frac{Δ\phi}{Δt}$
N = Number of turns = 500
$Δ\phi$ = Change in flux = $(7-3)×10^{-5}Wb=4×10^{-5}Wb$
$Δt$ = time internal = 0.015
$ε=-500×\frac{-4×10^{-5}}{0.01}=2V$
$I=\frac{ε}{R}=\frac{2}{10}=0.2A$ [By ohm's law]