Frequency, wavelength and phase speed
Relate a periodic wave's spatial and temporal repetition.
Key knowledge
For a traveling periodic wave component, phase speed equals frequency times wavelength: v_phase = fλ. This is the speed of a phase pattern, which need not equal particle speed or signal speed.
Values and equations
v_phase = fλ = ω/k
- v_phase
- Phase speed m s⁻¹
- f
- Positive frequency Hz
- λ
- Positive wavelength m
- ω
- Positive angular frequency rad s⁻¹
- k
- Positive angular wavenumber rad m⁻¹
Conditions and scope
- f and λ refer to the same wave component in the same medium and reference frame; f, λ, ω and k are positive magnitudes in this speed formula.
- In a dispersive medium, phase speed can depend on frequency.
Sources · 3
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
- University Physics, volume 1: Mathematics of WavesSamuel J. Ling, Jeff Sanny and William Moebs / OpenStax, Rice UniversityTextbook chapter
- 8.03SC Vibrations and Waves (2016), Lecture 13: dispersionMassachusetts Institute of Technology — MIT OpenCourseWareCourse notes · PDF
- Waves · Physics (2026–27 reprint)National Council of Educational Research and Training (NCERT)Textbook chapter · PDF
Evidence and review
OpenStax 16.2: v = ω/k = λ/T; MIT Lecture 13 pages 1–3: pulse information, frequency-dependent phase speeds and group/phase distinction.
2026-10-10 · Periodic phase relation and its dispersion caveat only; no group-velocity or information-velocity equality is asserted.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Scope or convention differs
Travelling-wave phase speed satisfies v=ω/k=fλ.
The chapter’s mechanical examples support phase propagation; particle, group and signal speeds require separate analysis.
National Council of Educational Research and Training (NCERT)
- Waves · Physics (2026–27 reprint) IndiaEnglish
14.3–14.4 constant-phase derivation
- Waves · Physics (2026–27 reprint)
Entry details
Permanent link to this entry ↗- Record identity
- physics-wave-speed
- Revision
- core.1
- Structured reference record
- Essential core · first collection · University core expansion