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Concepts Of Physics MCQ Edition [Volume 2]
Exam
Concepts Of Physics MCQ Edition [Volume 2]
Subject
Physics
Chapter
Magnetic Field due to a Current

Concepts Of Physics MCQ Edition [Volume 2] · Physics · Magnetic Field due to a Current

A circular coil carrying current has 100 turns and a radius of 5.0...

A circular coil carrying current has 100100 turns and a radius of 5.0 cm5.0 \text{ cm}. It generates a magnetic field of 6.0×10−5 T6.0 \times 10^{-5} \text{ T} at its centre. Determine the magnitude of the current.

Options

  1. A0.096 A0.096 \text{ A}
  2. B0.048 A0.048 \text{ A}
  3. C0.024 A0.024 \text{ A}
  4. D0.48 A0.48 \text{ A}

Correct answer

B. 0.048 A0.048 \text{ A}

Step-by-step solution

The magnetic field at the centre of a circular coil of NN turns is given by:

B=μ0NI2RB = \dfrac{\mu_0 N I}{2R}

Rearranging for current II:

I=B×2Rμ0NI = \dfrac{B \times 2R}{\mu_0 N}

Substituting the given values, B=6.0×10−5 TB = 6.0 \times 10^{-5} \text{ T}, R=5.0 cm=0.05 mR = 5.0 \text{ cm} = 0.05 \text{ m}, N=100N = 100, and μ0=4π×10−7 T⋅m/A\mu_0 = 4\pi \times 10^{-7} \text{ T}\cdot\text{m/A}:

I=6.0×10−5×2×0.054π×10−7×100I = \dfrac{6.0 \times 10^{-5} \times 2 \times 0.05}{4\pi \times 10^{-7} \times 100}

I=6.0×10−64π×10−5I = \dfrac{6.0 \times 10^{-6}}{4\pi \times 10^{-5}}

I=0.15π AI = \dfrac{0.15}{\pi} \text{ A}

Using π≈3.14\pi \approx 3.14:

I≈0.153.14≈0.048 AI \approx \dfrac{0.15}{3.14} \approx 0.048 \text{ A}
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