Practice question

Given: A solenoid produces B = 1.2 T with a core of μ_r = 400 and n = 1500 m^{-1 . What is the current I ? (Take μ_0 = 4π × 10⁻⁷T m A^{-1 ). Formula: B = μ_0 μ_r n I, so I = B/μ_0 μ_r n. Substitution & Calculation: Given: B = 1.2 T, μ_r = 400, n = 1500 m^{-1, μ_0 = 4π × 10⁻⁷. I = frac1.24π × 10⁻⁷ × 400 × 1500 = frac1.27.539 × 10⁻¹approx 1.592 A approx 1.6 A . Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.