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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 consisting of 200 turns has a radius of 10 cm and...

A circular coil consisting of 200200 turns has a radius of 10 cm10 \text{ cm} and carries a current of 2.0 A2.0 \text{ A}. Determine the magnitude of the magnetic field B⃗\vec{B} at the centre of the coil.

Options

  1. A2.51 mT2.51 \text{ mT}
  2. B5.02 mT5.02 \text{ mT}
  3. C3.14 mT3.14 \text{ mT}
  4. D1.26 mT1.26 \text{ mT}

Correct answer

A. 2.51 mT2.51 \text{ mT}

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}

Given parameters:
N=200N = 200
R=10 cm=0.1 mR = 10 \text{ cm} = 0.1 \text{ m}
I=2.0 AI = 2.0 \text{ A}
μ0=4π×10−7 T⋅m/A\mu_0 = 4\pi \times 10^{-7} \text{ T}\cdot\text{m/A}

Substituting the values into the formula:

B=4π×10−7×200×2.02×0.1B = \dfrac{4\pi \times 10^{-7} \times 200 \times 2.0}{2 \times 0.1}

B=1600π×10−70.2B = \dfrac{1600\pi \times 10^{-7}}{0.2}

B=8000π×10−7 TB = 8000\pi \times 10^{-7} \text{ T}

B=8π×10−4 TB = 8\pi \times 10^{-4} \text{ T}

Using π≈3.14\pi \approx 3.14:

B=8×3.14×10−4 TB = 8 \times 3.14 \times 10^{-4} \text{ T}

B=25.12×10−4 TB = 25.12 \times 10^{-4} \text{ T}

B=2.51×10−3 T=2.51 mTB = 2.51 \times 10^{-3} \text{ T} = 2.51 \text{ mT}
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