When a wave transitions from one medium to another, its wavelength and speed can change, but its frequency remains constant. This is due to the principle of conservation of energy, where frequency is determined by the source of the wave and does not change as the wave moves through different media.
In your scenario, the wavelength triples. When the wavelength increases, the speed of the wave must also increase since the relationship between speed (v), frequency (f), and wavelength (λ) is given by the equation:
\[ v = f \cdot \lambda \]
If the wavelength (λ) triples and the frequency (f) remains constant, the speed (v) must also triple to maintain the equation's validity.
Therefore, the correct statement is:
The speed will triple, and the frequency will stay the same.