Practice question

Given: Two parallel wires 0.02 m apart carry 10 A and 3 A in the same direction. What is the force per unit length? ( μ_0 = 4 π × 10⁻⁷ T m/A ) These values define the system as per NCERT data. Formula: f = μ_0 I_1 I_2/2 π d. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: f = frac4 π × 10⁻⁷ × 10 × 32 π × 0.02 = frac120 × 10⁻⁷⁰.04 = 3 × 10⁻⁵ N/m . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.