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. ε = N (Δ Φ/Δ t) . Δ Φ = 0.025 Wb , Δ t = 0.05 s , N = 90 . ε = 90 × (0.025/0.05) = 90 × 0.5 = 45 V . Using Φ = B A cosθ, e = -N dΦ/dt =