Wavelength and frequency are inversely related in electromagnetic waves. Higher wavelength means lower frequency, and vice versa. This is because speed (c) of an electromagnetic wave is constant, and c = λf. When wavelength increases, the number of wave cycles (frequency) within a second must decrease to maintain the constant speed. This relationship helps define the electromagnetic spectrum, where high-frequency waves (e.g., gamma rays) have short wavelengths, while low-frequency waves (e.g., radio waves) have long wavelengths.