What's the relationship btw frequency, wavelength, and temp?

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Discussion Overview

The discussion centers around the relationship between frequency, wavelength, and temperature, particularly in the context of sound waves and their behavior in different media. Participants explore how changes in temperature affect the speed of sound, frequency, and wavelength, with a focus on brass instruments and the physics of vibrating air columns.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant notes the equation v = f * λ and questions how changing temperature affects wavelength and frequency, suggesting that speed of sound increases with temperature.
  • Another participant challenges the assumption that frequency changes with temperature, seeking clarification on the context of sound waves in a medium.
  • A participant discusses the effect of temperature on the pitch of brass instruments, indicating that the pitch changes due to temperature variations affecting the speed of sound.
  • One participant explains that if the dimensions of the tube remain constant, the resonance wavelengths stay the same, but frequency changes due to increased speed of sound with temperature.
  • Another participant mentions that the intensity of wavelength increases with temperature, asserting that wavelength is inversely proportional to temperature, while frequency is directly proportional, but notes that frequency may not be affected in sound waves due to changes in speed related to molecular kinetic energy.

Areas of Agreement / Disagreement

Participants express differing views on whether frequency changes with temperature, with some asserting it does and others questioning this assumption. The discussion remains unresolved regarding the exact relationships and effects of temperature on frequency and wavelength.

Contextual Notes

Participants reference various assumptions about the behavior of sound waves in different media and the physical properties of materials, such as the expansion of metals and the speed of sound in gases, without reaching a consensus on the implications of these factors.

jwkhjang
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I'm currently studying wavelength and frequency and I've learned about the equation v= f*Lambda. What will happen if temperature is changed? I know that speed of the sound will increase. Does it mean that wavelength will also increase? I was curious because if temp. increases, the frequency increases which mean is that both speed of the sound and the temp will increase. So will the wavelength stay the same?
 
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jwkhjang said:
I'm currently studying wavelength and frequency and I've learned about the equation v= f*Lambda. What will happen if temperature is changed? I know that speed of the sound will increase. Does it mean that wavelength will also increase?
Yes.

jwkhjang said:
I was curious because if temp. increases, the frequency increases
Why would the frequency change with temperature? I assume that you are talking about sound waves traveling through some medium.
 
DrClaude said:
Yes.Why would the frequency change with temperature? I assume that you are talking about sound waves traveling through some medium.

Thanks for answering! Oh I'm investigating the effect of temperature change on the tune (frequency) of a brass instrument (only for vibrating air columns). I've learned that the tune of a pitch changes slightly due to the change in temp. Then will the wavelength stay the same?
 
In this case the pitch depends on the "matching" between the size of the tube and some fraction of the wavelength of the standing waves established in the tube.
If the change in the dimensions of the tube with temperature is negligible, the resonance wavelengths remain the same but as the speed of sound changes the frequency changes as well.

A more drastic effect you achieve by replacing air with a different gas, with different speed of sound. Like when you inhale helium. Your resonant cavities remain the same so the same wavelengths will resonate but the pitch of your voice increases.

In the case of temperature increase the tube itself expands a little but possibly the effect of increased speed is larger. You can do some estimates.
The increase in speed of sound in air is about 0.6 m/s for 1 degree Celsius. This is of the order of 0.1%.
The expansion of metals is of the order of 10-5 per degree or 0.001 % . So the effect of speed of sound is the dominant effect.
 
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The intensity of wavelength increases with increase in temp and the wavelength itself decreases so the wavelength is inversely proportional to temp and the frequency is directly proportional to temp, but in case of sound waves frequency is not effected the change in speed is due to the fact that the average kinetic energy of the molecules of the medium is directly proportional to temp.
 

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