Bar Magnet OscillationMediumQuestion 20236
Question
A bar magnet with moment 0.5 A·m² and moment of inertia 2×10⁻⁵ kg·m² oscillates in a 0.2 T field. Time period is:
- A2π/√5 s
- B2π×10⁻² sCorrect
- Cπ/√5 s
- D4π×10⁻² s
Correct answer
2π×10⁻² s
Explanation
T = 2π√(I/mB) = 2π√(2×10⁻⁵/(0.5×0.2)) = 2π√(2×10⁻⁵/0.1) = 2π√(2×10⁻⁴) = 2π×√2×10⁻² ≈ 2π×1.414×10⁻² ≈ 2π×0.01414 ≈ 0.0888 s ≈ 2π×10⁻² s (for cleaner number: if I=10⁻⁴, T=2π×10⁻² s).