If wavelength increases, frequency does what?

If wavelength increases, frequency does what?

• A. Increases
• B. Remains unchanged
• C. Decreases
• D. Cannot be determined

Answer: (C)

Wavelength and frequency are linked by the wave speed: v = fλ. In a given medium, the speed v is fixed, so if the wavelength λ increases, the frequency f must decrease to keep the product fλ equal to v. Physically, longer spacing between crests means fewer crests pass a point each second, so the frequency goes down. For light in vacuum, where v = c, doubling the wavelength halves the frequency. So increasing wavelength leads to a decrease in frequency.

Wavelength and frequency are linked by the wave speed: v = fλ. In a given medium, the speed v is fixed, so if the wavelength λ increases, the frequency f must decrease to keep the product fλ equal to v. Physically, longer spacing between crests means fewer crests pass a point each second, so the frequency goes down. For light in vacuum, where v = c, doubling the wavelength halves the frequency. So increasing wavelength leads to a decrease in frequency.