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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

Determine the maximum magnitude of the magnetic field B produced by...

Determine the maximum magnitude of the magnetic field B⃗\vec{B} produced by a copper wire having a diameter of 1.6 mm1.6 \text{ mm} and carrying a current of 20 A20 \text{ A}.

Options

  1. A1.0×10−2 T1.0 \times 10^{-2} \text{ T}
  2. B5.0×10−4 T5.0 \times 10^{-4} \text{ T}
  3. C5.0×10−3 T5.0 \times 10^{-3} \text{ T}
  4. D2.5×10−3 T2.5 \times 10^{-3} \text{ T}

Correct answer

C. 5.0×10−3 T5.0 \times 10^{-3} \text{ T}

Step-by-step solution

Given:
Diameter of the wire, d=1.6 mmd = 1.6 \text{ mm}
Radius of the wire, R=d2=0.8 mm=0.8×10−3 mR = \dfrac{d}{2} = 0.8 \text{ mm} = 0.8 \times 10^{-3} \text{ m}
Current, I=20 AI = 20 \text{ A}

The magnetic field produced by a current-carrying wire is maximum at its surface.
Using Ampere's law, the maximum magnetic field is given by:
B_{\text\max} = \dfrac{\mu_0 I}{2 \pi R}

Substituting the given values:
B_{\text\max} = \dfrac{4 \pi \times 10^{-7} \times 20}{2 \pi \times 0.8 \times 10^{-3}}

B_{\text\max} = \dfrac{2 \times 10^{-7} \times 20}{0.8 \times 10^{-3}}

B_{\text\max} = \dfrac{40 \times 10^{-7}}{8 \times 10^{-4}}

B_{\text\max} = 5.0 \times 10^{-3} \text{ T}
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