Question

A wave's _______________ and its frequency have a reciprocal relationship.

Answer 1

Wavelength and frequency have a reciprocal relationship. If one doubles, the other halves.

Answer 2

wave frequency and its wavelength is related by the following relation

$frequency = \frac{speed}{wavelength}$

we can also show this by

$f = \frac{v}{\lambda}$

now if speed of the wave remains constant then we can say that frequency of wave is inversely depends on the wavelength.

so we can say

wavelength of wave is inversely depends on its frequency