Q175 / 200 · Manipal (MET) 2010 · Physics

A disc of radius 0.1 m is rotating with a frequency $10 \mathrm{rev} / \mathrm{s}$ in a normal magnetic field of strength 0.1 T . Net induced emf is

  • A
    $2 \pi \times 10^{-2} V$
  • Correct answer
    B
    $\pi \times 10^{-2} \mathrm{~V}$
  • C
    $\frac{\pi}{2} \times 10^{-2} \mathrm{~V}$
  • D
    None of these

Solution

Net induced emf due to disc is $\begin{aligned} \varepsilon & =\frac{1}{2} B \omega l^2 \\ & =\frac{1}{2} \times 0.1 \times 2 \pi \times 10 \times 0.1 \times 0.1 \\ & =\pi \times 10^{-2} \mathrm{~V}\end{aligned}$

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

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