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Two parallel wires 0.05 m apart carry currents of 8 A and 12 A in the same direction. The force per unit length on the 8 A wire is (μ₀ = 4π × 10⁻⁷ T·m/A):

Correct answer: A. 3.84 × 10⁻⁴ N/m

  • A. 3.84 × 10⁻⁴ N/m
  • B. 7.68 × 10⁻⁴ N/m
  • C. 1.92 × 10⁻⁴ N/m
  • D. 5.76 × 10⁻⁴ N/m

Explanation

Force per unit length F/L = (μ₀I₁I₂)/(2πd). Substituting μ₀ = 4π × 10⁻⁷, I₁ = 8 A, I₂ = 12 A, d = 0.05 m. F/L = (4π × 10⁻⁷ × 8 × 12)/(2π × 0.05) = 3.84 × 10⁻⁴ N/m (attractive).

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