Practice question

**Field decreasing to zero** induces emf trying to maintain field, current direction such that its field adds to original. For 150 turns area 0.06 m² B 0.14 T to zero in 0.3 s, e=150×0.06×0.14/0.3=4.2 V, as earlier, showing linear dependence on N, A, ΔB/Δt. ε = N (Δ Φ/Δ t) . Δ Φ = 0.06 Wb , Δ t = 0.12 s , N = 130 . ε = 130 × (0.06/0.12) = 130 × 0.5 = 65 V . Using Φ = B A cosθ, e = -N dΦ/dt = -N A dB/dt = B l v = N B A ω sinωt, L