- #1
En Joy
- 16
- 0
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The discussion centers on the confusion surrounding the Rayleigh-Jeans law, particularly regarding the use of different units in spectral density expressions. Participants clarify that one formula refers to density per unit wavelength while the other refers to density per unit frequency, leading to different dimensional units. A correction is made regarding the notation, specifying that the first expression should use ν instead of λ. The conversation emphasizes the importance of ensuring that comparisons are made between equivalent units to avoid misunderstandings. Overall, the thread highlights the need for clarity when discussing physical laws and their mathematical representations.
- #2
Jilang
- 1,116
- 72
Are you taking these expressions from two different texts? They may be using different units.
- #3
soarce
- 154
- 24
In the second formula you have an additional lambda in the denominator. Maybe one should refer to spectral density in terms of frequency of in terms of wavelength, i.e. ##u_\nu## and ##u_\lambda##.
- #4
fireflies
- 210
- 12
Why (wavelength) ^4?
Shouldn't it be (wavelength) ^3??
Then dimensions are same
Shouldn't it be (wavelength) ^3??
Then dimensions are same
- #5
En Joy
- 16
- 0
No they are in same page of a book !Jilang said:
- #6
En Joy
- 16
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Sorry guys, in the first expression this should be ν in the sub script instead of λ.En Joy said:
- #7
Jilang
- 1,116
- 72
Ah. Then you are not comparing apples with apples! One is the density per unit wavelength and one is per unit frequency. They would not be expected to have the same units. They are different things.
- #8
En Joy
- 16
- 0
Thank youJilang said: