Wave Speed Relation v = fλ
The wave speed relation states that speed of a wave equals frequency multiplied by wavelength, written as v = fλ.
Practice This ConceptMain explanation
Teacher explanation
In the formula v = fλ, v is wave speed in metre per second, f is frequency in hertz, and λ is wavelength in metre. It is used when any two of speed, frequency, and wavelength are given. Correct unit conversion is important, especially when wavelength is given in centimetres.
Example
If sound has frequency 170 Hz and wavelength 2 m, its speed is v = 170 × 2 = 340 m/s.
Simple analogy
Speed equals how often times how long each wave is.
Common confusion
Students often forget to convert centimetres to metres before using v = fλ.
Exam tip
Write the formula first, substitute with units, and check whether the final unit is m/s, Hz, or m.
Study the wave speed relation v = fλ diagram carefully
Use the labelled diagram to keep wave speed relation v = fλ clear in short answers and revision.
What this diagram makes clear
This diagram keeps the labels and direction of wave speed relation v = fλ in the right order.
Where this helps in exams
Use this for labelled diagram work and short exam answers on wave speed relation v = fλ.
Revision cue
Revise wave speed relation v = fλ through the labels before writing the answer.
Answer writing and exam use
1-mark use
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2-mark use
Define wave speed relation v = fλ and add one example or condition.
3-mark use
Explain wave speed relation v = fλ, show the method or example, and mention the common mistake.
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