Wavelength and frequency are ______ related.

• A. Inversely related
• B. They are independent
• C. Directly related
• D. They are reciprocal

Answer: (C)

Wavelength and frequency are linked through the wave’s speed: v = f λ. When the speed is fixed, increasing frequency must produce a smaller wavelength to keep the product f λ equal to v. In other words, they move in opposite directions; as one goes up, the other goes down. This inverse relationship is especially clear for light in a vacuum, where the speed c is constant, so f = c/λ. If the frequency doubles, the wavelength halves. They aren’t independent and aren’t directly proportional, and while you’ll sometimes hear about reciprocal relationships, the precise statement is that frequency and wavelength are inversely related through the wave’s speed.