Faraday + Lenz: EMF = −dΦ/dt; negative sign means induced I opposes flux change (energy conservation); N turns: multiply by N.

Motional EMF and rotating coil: ε = Bvl (rod); ε_{0} = NBAω (coil); peak when coil is parallel to B; polarity from F = qv × B.

AC phase: ELI (inductor: V leads I, wattless); ICE (capacitor: I leads V, wattless); R in phase, power = $V_{rms}$ $I_{rms}$.

LCR resonance: Z = R (minimum, NOT zero); $f_{0}$ = $\frac{1}{2π√LC}$; I max; φ = 0; power max.

Transformer: $V_s$/$V_p$ = $\frac{N_s}{N_p}$; I ratio is INVERSE; step-up: high V, low I; losses: copper ($I^{2}$R), eddy (lamination), hysteresis (soft iron), flux leakage.