Practice question

**Maximum emf** e₀ = N B A ω, for 180 turns A=0.02 m² B=0.03 T ω=60 rad/s, e₀=180×0.03×0.02×60=6.48 V, illustrating dependence on N, B, A, ω, used in generator design, increasing N or B or A or ω raises output. A = π r² = 3.14 × (0.04)² = 0.005024 m² . ε₀ = N B A ω = 250 × 0.06 × 0.005024 × 40 = 3.0144 V ≈ 3.01 V . Using Φ = B A cosθ, e = -N dΦ/dt = -N A dB/dt = B l v = N B A ω sinωt, L = μ₀ N²A/l, M = e/(dI/dt) and