Characteristic Impedance Sets Launched Current - Magnetism, Induction, and Transmission Lines Step by Step

A characteristic-impedance-sets-launched-current scan fixes a line impedance and checks that a launched voltage step draws current I = V / Z0, here 12 V into 4 ohm giving 3 A. The arithmetic is exact only for the stated voltages, line impedances, currents, and rows in the ideal uniform-line, characteristic-impedance model. Real lines add loss, dispersion, connector mismatch, source impedance, finite rise time, probe/calibration limits, finite precision, and measurement uncertainty.

A stated line impedance fixes the current carried by a voltage step. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

The line impedance sets the launched current

A 12 volt step into a 4 ohm line launches 3 amperes.

I_{+}=12\ \text{V}\div 4\ \Omega=3\ \text{A}