Electromagnetic Induction - Result Question 7
7. A coil of resistance $400 \Omega$ is placed in a magnetic field. If the magnetic flux $\phi$ (wb) linked with the coil varies with time $t$ (sec) as $\phi=50 t^{2}+4$. The current in the coil at $t=2 sec$ is :
[2012]
(a) $0.5 A$
(b) $0.1 A$
(c) $2 A$
(d) $1 A$
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Answer:
Correct Answer: 7. (a)
Solution:
- (a) According, to Faraday’s law of induction
Induced e.m.f. $\varepsilon=-\frac{d \phi}{d t}=-(100 t)$
Induced current $i$ at $t=2 sec$.
$=|\frac{\varepsilon}{R}|=+\frac{100 \times 2}{400}=+0.5 A$
The magnetic flux linked with a loop does not change when magnet and loop are moving with the same velocity.
