Practice question

**Uniform field change** in coil produces emf proportional to area and turns, for circular coil radius 0.16 m area πr²=0.0804 m², B 0.12 T deformed to wire in 0.6 s, ΔΦ=0.12×0.0804=0.00965 Wb, e=0.00965/0.6=0.0161 V, illustrating area change also induces emf. Given: N = 50 , Δ Φ_B = 0.02 - 0 = 0.02 Wb , Δ t = 0.1 s . Using Faraday's law: ε = -N (Δ Φ_B/Δ t) . ε = 50 × (0.02/0.1) = 50 × 0.2 = 10 V . Magnitude of emf = 10 V. Using Φ = B A cosθ, e = -N dΦ/dt = -N A dB/dt =