The relationship between frequency and wavelength in waves is inversely proportional. According to the wave equation, the speed of a wave is equal to the product of its frequency (f) and wavelength (λ): v = f × λ. When the frequency increases, the wavelength decreases, and vice versa, as the speed of the wave remains constant in a given medium. This relationship is crucial in understanding various phenomena, such as light and sound waves, and is fundamental to fields like acoustics and optics.