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TS EAMCET · Physics · Electromagnetic Induction

The plane of a circular coil of resistance \(7.5 \Omega\) is placed perpendicular to a uniform magnetic field. The flux \(\phi\) (in weber) through the coil varies with time \(t\) (in second) as \(\phi=2 t^2+3 t-2\). The induced power in the coil at time \(t=3 s\) is

  1. A 7.5 W
  2. B 15 W
  3. C 30 W
  4. D 20 W
Verified Solution

Answer & Solution

Correct Answer

(C) 30 W

Step-by-step Solution

Detailed explanation

\( \varepsilon = -\frac{d\phi}{dt} = -\frac{d}{dt}(2 t^2+3 t-2) = -(4t+3) \) \( |\varepsilon|_{t=3s} = |-(4(3)+3)| = |-12-3| = 15 \, V \) \( P = \frac{\varepsilon^2}{R} = \frac{(15)^2}{7.5} = \frac{225}{7.5} = 30 \, W \)
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