✓ Sources checked · 10 September 2026 · View verification
Frequency is the number of cycles per second of a periodic signal. Its unit is hertz, Hz = s⁻¹, and it is the reciprocal of the period.
By Matan · Updated
Time repetition and spatial repetition differ
Use f = 1/T and angular frequency ω = 2πf. Wavelength requires the phase speed as well: λ = v/f. The frequency does not determine amplitude, and carrier frequency alone does not determine a communication channel’s bandwidth. [1]
Worked cycle count
A stable signal completes 120 cycles in 0.50 s. Frequency is 240 Hz, period 0.00417 s or 4.17 ms, and angular frequency about 1508 rad/s. If it is sound traveling at 343 m/s, wavelength is 1.43 m. Counting 120 crests from the first crest to the last would instead span 119 intervals, so define the counting method.
A higher note can be quieter
Two tones may have different frequencies and the same pressure amplitude, or a higher-frequency tone may have a smaller amplitude. Their perceived loudness can still differ because hearing sensitivity varies with frequency. There is no universal amplitude-proportional-to-frequency law.
A pulse has a spectrum
A complex or changing signal may contain many frequencies, so one cycle rate is not always sufficient. At a stationary linear boundary, transmitted frequency remains the same while wavelength can change. Moving sources and observers can produce Doppler shifts.
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How this article was checked
Sources checked; calculations checked where shown. Main claims and model assumptions were checked against the references below. Example arithmetic and units were checked separately. Numerical examples are illustrative calculations, not experimental measurements.
Source checking and editing assisted by AI. No independent human scientific review is recorded for this revision. This record applies to the version dated 10 September 2026.
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Cite this article
Matan. “Wave frequency.” Your Physicist. Originally published 2023-03-20; updated 2026-09-10. https://your-physicist.com/wave-frequency/
Revision history
10 September 2026: Removed false amplitude and bandwidth dependencies and added count, period and angular-frequency conversions. Added references and a transparent verification record.
