Wave Speed Formula
The wave speed formula v = fλ relates the speed of a wave to its frequency and wavelength.
Essential for sound, light, and wave physics.
The Formula
The speed of a wave equals its frequency multiplied by its wavelength. This applies to all types of waves: sound, light, water, and more.
Variables
| Symbol | Meaning |
|---|---|
| v | Wave speed (measured in meters per second, m/s) |
| f | Frequency (measured in hertz, Hz, which means cycles per second) |
| λ | Wavelength (measured in meters, m) |
Example 1
A sound wave has a frequency of 440 Hz (the note A4). The speed of sound in air is 343 m/s. What is the wavelength?
Rearrange: λ = v / f
λ = 343 / 440
λ ≈ 0.78 m (about 78 cm)
Example 2
A radio station broadcasts at a frequency of 100 MHz. Radio waves travel at the speed of light (3 × 10⁸ m/s). What is the wavelength?
Convert frequency: 100 MHz = 100 × 10⁶ = 10⁸ Hz
Rearrange: λ = v / f = (3 × 10⁸) / (10⁸)
λ = 3 m
When to Use It
Use the wave speed formula for any problem relating wave speed, frequency, and wavelength.
- Sound wave calculations (music, acoustics, sonar)
- Light and electromagnetic wave problems
- Water wave analysis
- Telecommunications (radio, TV, Wi-Fi frequencies)