Wave Speed

Waves & Optics · 1636

Equation: v = f λ
Field: Waves & Optics
Symbols: v speed of the wave · f frequency, cycles per second · λ wavelength, the distance between repeats
Year: 1636

Significance

A wave advances one wavelength every cycle. Fix the speed — sound in air, light in vacuum — and frequency and wavelength are one quantity written two ways: 440 Hz is 78 cm of air, green light is 5.5 × 10¹⁴ Hz. Mersenne measured it for strings in 1636. Doppler, refraction, standing waves and every spectrum on the cosmos page start here.

Instruments

Atacama Large Millimeter/submillimeter Array (ALMA)

Required By

Standing Waves Refractive Index Doppler Effect Wave Equation Newton–Laplace Speed of Sound Bragg's Law Diffraction Grating Equation Gaussian Beam Divergence De Broglie Wavelength Planck–Einstein Relation Airy Diffraction Pattern

Referenced by

equation

Airy Diffraction Pattern Bragg's Law De Broglie Wavelength Diffraction Grating Equation Doppler Effect Gaussian Beam Divergence Newton–Laplace Speed of Sound Planck–Einstein Relation Refractive Index Standing Waves Wave Equation

instrument

Atacama Large Millimeter/submillimeter Array (ALMA)

Open on the Equations shelf — the interactive card, the filters, and everything alongside it.

From the Equations database in Notion, last edited 2026-08-18. This page is the row, rendered by the build; nothing on it is written by hand.