Is hv/kt Dimensionless in Planck's Radiation Law?

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Discussion Overview

The discussion centers around the dimensional analysis of the expression hv/kt in Planck's radiation law, specifically whether it is dimensionless. Participants explore the units of the constants involved and their implications for the expression's dimensionality.

Discussion Character

  • Technical explanation

Main Points Raised

  • One participant expresses confusion about the dimensionality of hv/kt and seeks assistance in understanding it.
  • Another participant asks for the units of h, k, v, and t to clarify the analysis.
  • Participants identify h as Planck's constant (Js), k as the Boltzmann constant (J/K), and t as temperature (K), while initially being uncertain about the units of v.
  • A participant clarifies that v refers to frequency (ν), which has units of 1/time, aiding in the dimensional analysis.
  • Following the clarification, one participant acknowledges that the dimensional analysis now makes sense and indicates that the units cancel appropriately.

Areas of Agreement / Disagreement

Participants seem to reach a mutual understanding regarding the identification of v as frequency and its role in the dimensional analysis, but the overall question of whether hv/kt is dimensionless remains open for further exploration.

Contextual Notes

The discussion does not resolve whether hv/kt is definitively dimensionless, as it relies on the proper identification and understanding of the units involved, which may still require further verification.

noreally
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Hi all!

It was stated that in planks radiation law by my lecturer thathv/kt is dimensionless but my mediocre brain can't do the analysis. Try as I might I also can't find the relevant units to prove it. If someone could help I would be eternally grateful.

p.s. This is my first post *virginity lost*
 
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What are the units of h, k, v, and t, separately?
 
h is planks constant (Js), k is the Boltzmann constant (J/k), t is temp (k) and v I am unsure on, which is why I am struggling. Thus far i got that they cancel to leave s(then units for v). Confirmation on v would be maybe a part 2 to my question. thanks for the reply!
 
noreally said:
h is planks constant (Js), k is the Boltzmann constant (J/k), t is temp (k) and v I am unsure on, which is why I am struggling. Thus far i got that they cancel to leave s(then units for v). Confirmation on v would be maybe a part 2 to my question. thanks for the reply!

What you have written as v is actually nu (see below) which is a frequency and has units of 1/time.

\nu
 
Thanks for the clarification, that makes sense and also in terms of the dimensional analysis which now cancels. Many thanks!
 

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