3. how did the speed of the wave change as the wavelength decreased?

Explanation:

Step1: Recall wave - speed formula

The speed of a wave is given by the formula $v = f\lambda$, where $v$ is the speed, $f$ is the frequency and $\lambda$ is the wavelength. In a given medium, the frequency of a wave is constant when the source of the wave is constant.

Step2: Analyze the relationship

Since $v = f\lambda$ and $f$ is constant, when $\lambda$ decreases, the speed $v$ also decreases proportionally.

Answer:

The speed of the wave decreases as the wavelength decreases when the frequency is constant.