# Refractive index of materials

## Main Question or Discussion Point

Hello all,
I want to know that refractive index of materials like cooper, zinc, aluminium, teflon, PMMA varies with the application of heat from room to 100°C and for negative temperatures 77k to 300k.

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Simon Bridge
Homework Helper
Welcome to PF;
The answer is yes - the refractive index of materials like that depend on temperature.
I don't know how you'd find out the specific temperature dependence of a material across the entire temperature range you are interested in - it is likely there will be useful information in an engineering and material science desk reference, and the rest will need a literature hunt. Teflon and PMMA are quite complicated but they are all well studied materials - I'd be surprised if the information was not available.

Some notes:
I am guessing you are not used to scientific conversations. One of the goals of this forum is to help people better communicate in a scientific way. To that end:

"a temperature of 77k" reads like this: "a temperature of 77000 Kelvin"
... because the lower case "k" is the metric prefix "kilo", and a temperature without explicit units is usually taken to be absolute "Kelvin".
(It is a very common shorthand to refer to kilo-something as a so-much "kay", with the actual unit implied by the situation.)
The SI symbol for "Kelvin" is an upper case "K".

It is not possible to have a negative temperature in Kelvins though. Presumably you are thinking of negative degrees centigrade?

300K would be a common approximation for "room temperature" - about 27degC, actually a tad on the warm side - but i.e. not negative.

In general, it is best to pick a unit and stick to it within the same bit of writing. Jumping around the units tends to lead to confusion ... or, at least, it makes the reader work harder than they need to.

* You wanted to know about the temperature range: 77 to 373K or -196 to 100 degC.

Hello Simon Bridge,
yeah i am not used to scientific conversations and its my first post on the forum.
Sorry for the confusion. its about the temperature range: 77 to 373K or -196 to 100 degC. i wanted to know.
i will follow up in future as you told.
thanks again

Simon Bridge
Homework Helper
No worries - cannot expect everyone to get it right first time ... ;)
It would be possible to provide a better answer if we knew the context for the question.

DrDu
The index of refraction of these substances varies only little in this temperature range. The main change is due to thermal expansion. So if you find the value of $n(T_1)$ for some temperature $T_1$ and it's density $\rho(T_1)$ then the index of refraction at another temperature is in good approximation $n(T_2)=n(T_1)\cdot \rho(T_2)/\rho(T_1)$.

Andy Resnick
Hello all,
I want to know that refractive index of materials like cooper, zinc, aluminium, teflon, PMMA varies with the application of heat from room to 100°C and for negative temperatures 77k to 300k.
This question is too vague to answer- what wavelength range?

http://srdata.nist.gov/gateway/gateway?property=refractive+index&proft=Submit&rddesc=desc
http://www.nist.gov/pml/div685/grp03/theory_calculation.cfm [Broken]