Problem 1 - Olympiad

A toroid of mean radius 0.40 m has 1500 turns. A circular loop of radius 0.01 m is placed normal to the magnetic field produced by the toroid. If the current in the toroid changes from 0 to 2 A in 0.003 s, the induced emf in the loop is closest to

A. 0.08 mVB. 0.16 mVC. 0.32 mVD. 0.64 mV

Correct: B

Magnetic field inside toroid B = μ₀Ni/(2πr). dΦ = N_loop·A_loop·dB = N_loop·πa²·μ₀N/(2πr)·di. |ε| = dΦ/dt = 1·π(0.01)²·(4π×10⁻⁷)(1500)/(2π·0.40)·(2/0.003) ≈ 0.16 mV.