current-power-ratio-three-row-scan - Electronic Circuits XV: Transformers and Coupled Inductors Step by Step

Secondary load-current rows keep primary and secondary power equal. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Ideal current changes only as much as equal power requires

The voltage ratio is fixed. Load current then fixes secondary power and primary current.

V_sI_s=V_pI_p

Three load-current rows keep both powers equal

The secondary current changes, and the primary current follows the inverse turns ratio.

\begin{array}{c|c|c|c}I_s&I_p&P_s&P_p\\1\ \text{A}&\tfrac{1}{2}\ \text{A}&6\ \text{W}&6\ \text{W}\\2\ \text{A}&1\ \text{A}&12\ \text{W}&12\ \text{W}\\4\ \text{A}&2\ \text{A}&24\ \text{W}&24\ \text{W}\\\end{array}

The current row is accepted because the two powers match

The final row displays both sides of the same ideal power ledger.

6\ \text{V}\cdot4\ \text{A}=12\ \text{V}\cdot2\ \text{A}=24\ \text{W}