Q192 / 200 · Manipal (MET) 2011 · Physics

A coil having an area of $2 \mathrm{~m}^2$ is placed in a magnetic field which changes from $1 \mathrm{~Wb} / \mathrm{m}^2$ to $4 \mathrm{~Wb} / \mathrm{m}^2$ in 2 s . The emf induced in the coil will be

  • A
    4 V
  • Correct answer
    B
    3 V
  • C
    2 V
  • D
    1 V

Solution

$\begin{aligned} & \text { Induced emf } e=n A \frac{d B}{d t} \\ & A=\text { area of coil }=2 m^2 \\ & \text { and } \\ & \qquad e=\frac{n=1}{2}+\frac{1 \times(4-1)}{2}=3 \mathrm{~V}\end{aligned}$

Hence, the correct answer is option: 'B'.

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