# Thread: Colour Temperature of Non-Blackbodies

1. ## Re: Re: Colour Temperature of Non-Blackbodies

Originally posted by Ian

thermodynamic scale (ie: Deg Kelvin) with a zero reference of -273.15 deg C.
Hi Ian,

just a minor, but very important point. The thermodynamic temperature scale (or absolute temperature scale) has a unit of kelvin designated as K, not °K (the degree symbol was officially dropped from kelvin in 1967). The degree symbol should only be used with the Celsius °C or Fahrenheit °F scale.

eg. the triple point of water is as follows in the various temperature scale.

273.16K = 0.01°C = 32.02°F

Just to make the point clear.

2. Originally posted by mervlam
btw, if i remember correctly, Black bodies got nothing to do with colour temperature. do correct me if it's wrong.

Colour temperature actually depends on the wavelength of the light emitted by an excited body. It involves a bit of Nuclear Physics concepts.
Just to make clear my point here. It's Quantum Mechanics concepts from Nuclear Physics

3. Originally posted by Sin
So the "black box with hole is a black body" thing is actually an analogy
yes, it's an analogy to make understanding easier.

4. ## Re: Re: Re: Colour Temperature of Non-Blackbodies

Originally posted by mervlam

Hi Ian,

just a minor, but very important point. The thermodynamic temperature scale (or absolute temperature scale) has a unit of kelvin designated as K, not °K (the degree symbol was officially dropped from kelvin in 1967). The degree symbol should only be used with the Celsius °C or Fahrenheit °F scale.
Very good merv, no go read what I said, no Degree symbol °K indicators were used What was used Deg Kelvin which is short for Degrees Kelvin which is *very* much is use still in the scientific community despite what the 13th CGPM changed it to in 1967.....

5. ## Re: Re: Re: Re: Colour Temperature of Non-Blackbodies

Originally posted by Ian

Very good merv, no go read what I said, no Degree symbol °K indicators were used What was used Deg Kelvin which is short for Degrees Kelvin which is *very* much is use still in the scientific community despite what the 13th CGPM changed it to in 1967.....
Hello,

don't want to argue with you. The SI unit for absolute temperture scale is Kelvin (K).

Anyway, as a joke, my lecturer said whoever puts the degree symbol in front of "kelvin" in the exams gets zero marks for that question.

6. Originally posted by mervlam

yes, it's an analogy to make understanding easier.
*with his most humble and apolegetic voice (so as to avoid misunderstandings)*

Thank you!

Well, I hope people don't blame me for misunderstanding the post about "A typical blackbody will be a box with just a small tiny hole. Light can go in but the hole appears to be black." The poster did assumed that everybody knew he was using an analogy.

ps: Another friend told me that he learned this in O levels! I mean we're the same age, how come it's in his classes and not in mine??

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