Wave speed, frequency and wavelength are linked by v = fλ. Use speed in m/s, frequency in Hz and wavelength in metres. At a fixed wave speed, a higher frequency means a shorter wavelength; convert centimetres or millimetres before substitution. Example: A wave has frequency 12 Hz and wavelength 15 cm. Calculate its speed. λ = 15 cm = 0.15 m; v = fλ = 12 × 0.15 = 1.8 m/s. Rearrange the relationship before substituting if a different quantity is required. Use clear labels. Consider the conditions.