A regulator-waste-is-input-minus-output scan closes a linear-regulator power ledger by splitting input power into useful load power and dissipated waste. The exact rows use the stated 7 V input, 5 V output, and load currents, so the voltage difference is spent at the same current. Real regulators have dropout curves, ripple, temperature limits, package thermal resistance, tolerance stacks, finite precision, and measurement uncertainty.
The input power budget closes as load plus waste. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
A linear regulator spends the voltage difference
The input minimum is 7 V while the output is 5 V. The difference is dissipated at the same load current.
Pwaste=(Vin−Vout)I
Input power closes as load plus waste in every row
The voltage difference stays fixed, so load power and waste power climb together with current.