1. ELI the ICE man (Phase Relationships)

E - L - I    →    In an inductor (L): Voltage (E) comes before Current (I)
                  ∴ Current LAGS voltage by 90°

I - C - E    →    In a capacitor (C): Current (I) comes before Voltage (E)
                  ∴ Current LEADS voltage by 90°

Mnemonic story: ELI is a man made of ICE. In the Inductor (L), the EMF (E) arrives early; in the Capacitor (C), the current (I) arrives early.

2. FLOP — Lenz's Law

F - L - O - P
Flux  Lenz  Opposes  Production

"The flux that Lenz's law produces opposes the production of change." If flux increases, the induced flux OPPOSES the increase. If flux decreases, induced flux SUPPORTS (opposes the decrease).

3. Transformer: Turns-Voltage-Current

"Turns and Voltage are Together (direct ratio)"
"Turns and Current are Contrary (inverse ratio)"

N_s > N_p → V_s > V_p → I_s < I_p
N_s < N_p → V_s < V_p → I_s > I_p

4. Resonance: Z = R (Minimum, NOT Zero)

At resonance: X_L = X_C (they CANCEL each other)
Z = √($R^{2}$ + 0^{2}) = R
"Reactances cancel, only R remains"
Z is MINIMUM (= R), I is MAXIMUM (= V/R)

5. RMS vs Mean

RMS   = $V_{0}$/√2  ≈ 0.707 $V_{0}$  (Root Mean Square: for POWER)
MEAN  = 2$V_{0}$/π  ≈ 0.637 $V_{0}$  (Half-cycle average: for rectified DC)
RMS > MEAN  (√2/2 > 2/π: approximately 0.707 > 0.637)