Answer:
Wavelength
Step-by-step explanation:
Velocity of a wave is given by
![v=f\lambda](https://img.qammunity.org/2022/formulas/physics/high-school/s0f3r05cj52ps0ex7v2ia65bwa3zegeyr3.png)
where
= Frequency of wave =
![f=(v)/(\lambda)](https://img.qammunity.org/2022/formulas/physics/college/j29ndkpkl6yjinl9efhj6ryczucvt3og5y.png)
= Wavelength of wave
We have the relation
![f\propto (1)/(\lambda)](https://img.qammunity.org/2022/formulas/physics/college/3cmelwppycy6i39oeu5pzavyzd10n5wilp.png)
Now, velocity of the wave in a given medium remains constant. So, if the frequency increases the wavelength must decrease in order to keep the velocity of the wave constant. Also if the frequency decreases the the wavelength increases.