thermal resistivity k/w to c/w

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#4
Kelvin

One say 273,15 and another one say 272,15...,
I say -273,16C, that's my memmory of the correct 0K point, don't forget the "-" sign! 😎

Anyhow, Kelvin is following the Celcius scale with the same increaments.

For instance:

0K = -273C
+10K = -263C
+273K = 0C

Cheers 🙂
 
#5
jwb said:
Lots of confusion in this department, stemming from this simple fact:

1C° = 1K°
1°C = 272.15 °K

Also 0C° = 0K° = 0F° :hot:
Click to expand...

Those are all wrong, but maybe that was what you meant?

0°C = 273.16K (note, not °K)
a change of +/- 1°C equals a change of +/- 1K
that is, T°C = (T+273.16)K

I am too tired for the Fahrenheits and nobody uses Reaumurs
anymore. 🙂

For the heatsinks it doesn't matter if you use K/W or °C/W,
the figures are the same since it is about relative temperature
change.
 
#7
jwb said:
Lots of confusion in this department, stemming from this simple fact:

1C° = 1K°
1°C = 272.15 °K

Also 0C° = 0K° = 0F° :hot:
Click to expand...

All heatsink calculations I've seen use Celsius. However, there seems to be confusion about these different scales.

The zero degree reference for the Kelvin scale is absolute zero, a theoretical coldest possible temperature. (The Kelvin scale is mainly used in physics, especially thermodynamics.)

The zero degree reference for the Celsius scale is the freezing point of water, which also happens to be about 273 degrees K. But a degree of change is the same on both scales, they are just offset due to different zero reference points.

Also, zero C is 32 F, not 0F.
 
#8
Ultima Thule said:


Didn't know about this but why not °K,
"°" means "grade" as far as i know. 🙂

For instance:
5°K = Five Grade Kelvin
5°C = Five Grade Celsius

What ever, to tire to think, I should go to sleep in my 295K cool bed! 😉
Click to expand...

I am sorry, but you are wrong. The SI unit is Kelvin only,
not degrees Kelvin. It is very common to see people
write °K but it is not correct. There are no degrees
on the Kelvin scale, there are only Kelvins. Confusing maybe,
but it is the SI standard. Actually, the degrees are redundant
on the other temperature scales too, but there it is standard,
or should we rather say common practice?, to write °C and °F.
 
#10
Christer said:


I am sorry, but you are wrong. The SI unit is Kelvin only,
not degrees Kelvin. It is very common to see people
write °K but it is not correct. There are no degrees
on the Kelvin scale, there are only Kelvins. Confusing maybe,
but it is the SI standard. Actually, the degrees are redundant
on the other temperature scales too, but there it is standard,
or should we rather say common practice?, to write °C and °F.
Click to expand...


Hi Christer,

thanks for your answer, well I didn't propose anything, just asked if the "°" sign is not used in combination with Kelvin since I didn't know.

By the way I mixed up between the words "grade" and "degrees", i meant of course "degrees" so there's my english language skills.
Det kanske kommer ifrån att jag tänkte på "grader" som i svenska språket... 🙂

Anyhow, now I know! 😉
 
#11
Ultima Thule said:



Hi Christer,

thanks for your answer, well I didn't propose anything, just asked if the "°" sign is not used in combination with Kelvin since I didn't know.

By the way I mixed up between the words "grade" and "degrees", i meant of course "degrees" so there's my english language skills.
Det kanske kommer ifrån att jag tänkte på "grader" som i svenska språket... 🙂

Anyhow, now I know! 😉
Click to expand...

Don't worry, writing °K is a very very common error, so I though I should point it out. Being swedish I had, of course, no problem at all to understand "grader". 🙂


To confuse people even more I might add that the original
scale proposed by Celsius had 100° at the freezing point
and 0° at the boiling point, that is, it was reversed wrt.
to how it is now used. 🙂
 
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