One wave, one source, two materials. Pick a medium for each side of the dashed boundary and watch the wavelength change as the wave crosses it — while the frequency, set once for the whole wave, stays exactly the same on both sides.
Medium 1 (left)
Medium 2 (right)
Medium 1 — Air
343 m/s
λ1 = 1.340 m
Medium 2 — Water
1482 m/s
λ2 = 5.789 m
Speed ratio v2 / v1
4.321
The wavelength ratio λ2 / λ1 is 4.321 — the same number.
Frequency f
256 Hz
Identical on both sides.
Frequency f256 Hz
String tension T68 N
Affects the String option only.
Fixed: string mass per length μ = 6.0 g/m. Gas and liquid speeds are quoted at
20 °C. The steel figure is the bulk longitudinal wave.
Try this: set both rows to Air. The two wavelengths match and the ratio reads 1.000 — a boundary with nothing on the other side of it.