An ideal wave links electric and magnetic amplitudes through a fixed exact speed. 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 checked wave fields share one exact speed
The electromagnetic claim uses exact training values: 6\ \text{m}/\text{s} and 2\ \text{T} produce a field of 12\ \text{V}/\text{m}.