Practice question

**Magnetic flux** Φ = B·A = B A cosθ, B magnetic field (T), A area (m²), θ angle between B and normal to area, unit Wb = T·m², Faraday's law induced emf e = -N dΦ/dt, N turns, negative sign Lenz's law indicating opposition, magnitude |e| = N |ΔΦ/Δt|, for 100 turns ΔΦ=0.03 Wb Δt=0.06 s e=100×0.03/0.06=50 V. Initial flux: Φ_i = B A cos 0° = 0.5 × 0.04 × 1 = 0.02 Wb . Final flux: Φ_f = B A cos 90° = 0.5 × 0.04 × 0 = 0 Wb . Δ Φ = 0.02 - 0 = 0.02 Wb , Δ