A long straight wire carries a current of 10 A along the z-axis. The magnetic field at a point (0.2 m, 0.3 m, 0) is (μ₀ = 4π × 10⁻⁷ T·m/A):
Correct answer: C. 5.55 × 10⁻⁶ T (out of plane)
- A. 2 × 10⁻⁶ T (out of plane)
- B. 4 × 10⁻⁶ T (into plane)
- C. 5.55 × 10⁻⁶ T (out of plane)
- D. 8 × 10⁻⁶ T (into plane)
Explanation
Magnetic field due to a long wire is B = (μoI)/(2πr). Distance r = √(0.22 + 0.32) = 0.36 m. B = (4π × 10−7 × 10)/(2π × 0.36) ≈ 5.55 × 10−6 T. Direction by right-hand rule is out of the plane (positive z).
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Magnetic flux density and magnetic flux describe the strength of a magnetic field and the field passing through a surface. A charged particle moving through a magnetic field experiences a force perpendicular to its velocity and may follow circular or helical motion, depending on the angle between velocity and field.
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