Apparatus Reference:
Cue Column | Notes Column
| Cue | Notes |
|---|---|
| Faraday's Laws | 1st: Changing flux → induces EMF. 2nd: EMF = −dΦ/dt |
| Lenz's Law | Induced current opposes the change in flux (energy conservation) |
| Motional EMF | ε = Bvl when v ⊥ B ⊥ l; polarity from F = qv × B |
| AC Phase: R | V and I in phase, φ = 0 |
| AC Phase: L | Current LAGS voltage by 90° (ELI) |
| AC Phase: C | Current LEADS voltage by 90° (ICE) |
| LCR Resonance | = → Z = R (min), I = max, φ = 0 |
| Transformer | / = ; current ratio INVERSE of turns ratio |
Summary
EMF = −dΦ/dt is the master equation of this chapter. The negative sign is Lenz's law. At resonance, Z = R (not zero). In transformers, when voltage steps up, current steps down. ELI the ICE man governs all phase relationships.