Transformer Equation — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Transformer Equation Applies to ideal transformers operating under alternating current where magnetic flux leakage is negligible. Apply Faraday's Law of Induction to both primary and secondary coils: E = -N d(Phi)/dt. Divide the secondary emf by the primary emf, assuming same rate of change of flux. For an ideal transformer, input power equals output power (V p I p = V s I s). Combine the voltage-turn ratio and power equality to derive the current ratio. Valid only for Alternating Current (AC). Current ratio assumes 100% efficiency (Ideal Transformer). Magnetic flux linkage must be perfectly shared between coils. Thinking transformers can step up DC voltage; they only work with changing magnetic flux. Assuming secondary current increases when secondary voltage increases; in a transformer, they are inversely related to maintain power conservation. Confusion between Step-up and Step-down: Step-up refers to voltage, not current.