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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 piece of wire carrying a current of 6.00 A is shaped into a...

A piece of wire carrying a current of 6.00 A6.00 \text{ A} is shaped into a circular arc of radius 10.0 cm10.0 \text{ cm}. If the arc subtends an angle of 120^{}^{{}^{\circ}} at the centre, determine the magnetic field BB produced by this piece of wire at the centre.

Options

  1. A3.77×10−5 T3.77 \times 10^{-5} \text{ T}
  2. B1.26×10−5 T1.26 \times 10^{-5} \text{ T}
  3. C1.88×10−5 T1.88 \times 10^{-5} \text{ T}
  4. D6.28×10−6 T6.28 \times 10^{-6} \text{ T}

Correct answer

B. 1.26×10−5 T1.26 \times 10^{-5} \text{ T}

Step-by-step solution

The magnetic field at the centre of a circular arc is given by:

B=μ0I4πrθB = \dfrac{\mu_0 I}{4\pi r} \theta

Given:
I=6.00 AI = 6.00 \text{ A}
r=10.0 cm=0.1 mr = 10.0 \text{ cm} = 0.1 \text{ m}
\theta = 120^{}^{{}^{\circ}} = \dfrac{2\pi}{3} \text{ rad}

Substituting the values:

B=4π×10−7×6.004π×0.1×2π3B = \dfrac{4\pi \times 10^{-7} \times 6.00}{4\pi \times 0.1} \times \dfrac{2\pi}{3}

B=10−6×60×2π3B = 10^{-6} \times 60 \times \dfrac{2\pi}{3}

B=40π×10−7 TB = 40\pi \times 10^{-7} \text{ T}

B=4×3.14×10−6 T=1.256×10−5 T≈1.26×10−5 TB = 4 \times 3.14 \times 10^{-6} \text{ T} = 1.256 \times 10^{-5} \text{ T} \approx 1.26 \times 10^{-5} \text{ T}
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