A longer-line-delays-the-same-step scan holds the signal speed fixed and varies the line length across rows, checking that the one-way delay t = length / speed scales with length row by row. The arithmetic is exact only for the stated lengths, signal speeds, delays, and rows in the ideal uniform-line, constant-speed model. Real lines add dispersion, loss, connector mismatch, finite rise time, cable tolerance, probe/calibration limits, finite precision, and measurement uncertainty.
Changing only length changes the one-way travel time. 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 shorter line gives the anchor delay
With length 12 meters and speed 3 meters per second, delay is 4 seconds.
12÷3=4
Doubling only length doubles the delay
With the same speed and length 24 meters, the delay becomes 8 seconds.