current-scale-keeps-power-ideal - Electronic Circuits XIII: Power, Rectification, and Regulation Step by Step

The ideal transformer current scale keeps input and output 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 power starts from the same voltage ratio

The checked secondary voltage is 8 V. The current scale is chosen so input power and output power close to the same value.

I_p=I_s{N_s \over N_p}

Every scanned current closes the same input-output ledger

Increasing secondary current raises both side powers together; the ideal transformer does not create an extra power row.

\begin{array}{c|c|c|c}I_s&I_p&P_{\text{out}}&P_{\text{in}}\\3\ \text{A}&1\ \text{A}&24\ \text{W}&24\ \text{W}\\6\ \text{A}&2\ \text{A}&48\ \text{W}&48\ \text{W}\\9\ \text{A}&3\ \text{A}&72\ \text{W}&72\ \text{W}\\\end{array}

Ideal current scale keeps power equal

The load side carries 3\ \text{A}. The ideal transformer current scale makes the primary carry 1\ \text{A}.

8\ \text{V}\cdot3\ \text{A}=24\ \text{W}=24\ \text{W}