Wave Frequency, Wavelength, and Wave Speed
All waves — sound, light, water, radio, and seismic waves — obey the fundamental wave equation: wave speed equals frequency times wavelength. This relationship connects the physical propagation speed of a wave to its oscillation frequency and spatial wavelength. Understanding it is essential for telecommunications, acoustics, optics, and medical imaging.
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Formula
Wave Frequency & Wavelength
Calculate wave frequency, wavelength, or wave speed using v = fλ.
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Worked Example
Given:
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FAQs
What is the speed of light and why is it important?
The speed of light in vacuum is exactly 299,792,458 m/s (approximately 3 × 10⁸ m/s). For light and all electromagnetic waves (radio, X-rays, microwaves), v = c in vacuum. Using the wave equation, visible light at 500 nm wavelength has a frequency of 6 × 10¹⁴ Hz.
What is the frequency range of human hearing?
Humans typically hear frequencies from about 20 Hz to 20,000 Hz (20 kHz). Sound below 20 Hz is infrasound; above 20 kHz is ultrasound. Hearing range narrows with age — adults often lose sensitivity above 15 kHz. Dogs and bats can hear ultrasound up to 65 kHz and 200 kHz respectively.
What is the relationship between frequency and energy for light?
For photons (light particles), energy = h × f where h is Planck's constant (6.626 × 10⁻³⁴ J·s). Higher frequency light (UV, X-rays, gamma rays) carries more energy per photon than lower frequency light (infrared, radio waves). This is why UV radiation can damage skin cells but radio waves cannot.