Practice question

**Faraday's first law** emf induced when flux linking coil changes, second law magnitude proportional to rate of change, e = -dΦ/dt, for N turns e = -N dΦ/dt, flux Φ = B A cosθ, change can be due to B change, A change, or θ change, all produce emf. ε = N (Δ Φ/Δ t) . Δ Φ = 0.04 Wb , Δ t = 0.08 s , N = 120 . ε = 120 × (0.04/0.08) = 120 × 0.5 = 60 V . Using Φ = B A cosθ, e = -N dΦ/dt = -N A dB/dt = B l v = N