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NEET PHYSICSEasy

A big circular coil with 10001000 turns and an average radius of 10 m10 \text{ m} is rotating about its horizontal diameter at a rate of 2 rad s12 \text{ rad s}^{-1}. The vertical component of the Earth's magnetic field at that location is 2×105 T2 \times 10^{-5} \text{ T}, and the electrical resistance of the coil is 12.56Ω12.56 \Omega. The maximum induced current in the coil will be:

A

2 A

B

0.25 A

C

1.5 A

D

1 A

Step-by-Step Solution

The maximum induced electromotive force (εmax\varepsilon_{max}) in a rotating coil is given by the formula εmax=NBAω\varepsilon_{max} = NBA\omega, where: NN is the number of turns (10001000). BB is the magnetic field (2×105 T2 \times 10^{-5} \text{ T}). AA is the area of the coil (πr2=π(10)2=100π m2\pi r^2 = \pi (10)^2 = 100\pi \text{ m}^2). ω\omega is the angular velocity (2 rad s12 \text{ rad s}^{-1}).

The maximum induced current (ImaxI_{max}) is given by Ohm's law: Imax=εmaxRI_{max} = \frac{\varepsilon_{max}}{R}.

Substituting the values: Imax=1000×(2×105)×(100π)×212.56I_{max} = \frac{1000 \times (2 \times 10^{-5}) \times (100\pi) \times 2}{12.56}

Noting that 12.564π12.56 \approx 4\pi: Imax=1000×2×105×100π×24πI_{max} = \frac{1000 \times 2 \times 10^{-5} \times 100\pi \times 2}{4\pi} Imax=400000π×1054πI_{max} = \frac{400000 \pi \times 10^{-5}}{4\pi} Imax=4π4π=1 AI_{max} = \frac{4\pi}{4\pi} = 1 \text{ A}.

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