Misconception 1: "Lenz's law and Faraday's law are separate laws"
Truth: Lenz's law is contained within Faraday's law. The negative sign in EMF = −dΦ/dt IS Lenz's law expressed mathematically. Faraday's second law gives magnitude; the negative sign (Lenz) gives direction.
Misconception 2: "High-frequency AC means more power from transformer"
Truth: An ideal transformer conserves power regardless of frequency. However, real transformers have frequency-dependent losses (eddy currents increase with frequency). For power transmission, 50 Hz is chosen as a balance between transformer efficiency and other practical factors.
Misconception 3: "The inductor stores energy by dissipating it as heat"
Truth: An ideal inductor stores energy in its magnetic field (U = ½) and returns ALL of it to the circuit—no heat dissipation. Only the coil's wire resistance causes heat. A superconducting inductor would store energy indefinitely with zero loss.
Misconception 4: "At resonance, all voltages (V_R, V_L, V_C) are equal"
Truth: At resonance, V_L = V_C (they cancel). V_R equals the supply voltage. V_L and V_C can individually be much larger than the supply voltage (voltage magnification by Q-factor).
Misconception 5: "The transformer works on DC current too"
Truth: Transformers work ONLY on AC. They require a changing magnetic flux (dΦ/dt ≠ 0) to induce EMF. With steady DC, the flux is constant and no EMF is induced in the secondary. (Induction coils for DC use a mechanical interrupter to artificially create changing flux.)
Misconception 6: "RMS means average"
Truth: RMS (Root Mean Square) is NOT the same as the arithmetic average. For sinusoidal AC: RMS = /√2, average (half cycle) = 2/π. The RMS value is higher than the mean, and it is the RMS value that is relevant for power calculations and ratings of electrical equipment.