Question:medium

A straight wire carrying of 14 A is bent into a semi-circular arc of radius 2.2 cm as shown in the figure. The magnetic field produced by the current at the centre (O) of the arc is ____ × 10–4 T.
A straight wire carrying of 14 A is bent into a semi-circular arc of radius 2.2 cm

Updated On: Mar 11, 2026
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Correct Answer: 2

Solution and Explanation

To determine the magnetic field at the center (O) of a semi-circular arc of wire, we use the Biot-Savart law. For a semi-circular arc, the magnetic field at the center is given by the formula:
B = (μ₀I)/(4R)
where:
  • μ₀ = 4π × 10-7 T·m/A (permeability of free space)
  • I = 14 A (current)
  • R = 0.022 m (radius)
Substituting the given values:
B = (4π × 10-7 T·m/A × 14 A) / (4 × 0.022 m)
Simplifying,
B = (56π × 10-7) / 0.088 T
B ≈ 2 × 10-4 T
This magnetic field value lies within the expected range (2 to 2). Thus, the magnetic field at the center is 2 × 10-4 T.
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