One of the key brand names tossed around in relation to smartphone and tablets this year has been Corning's Gorilla Glass. Next year, it may be Lotus Glass. Corning announced Lotus' commercial availability yesterday, and immediately began touting the display material's suitability for "cutting-edge technologies", including OLED …
"Scientifically, its coefficient of thermal expansion from 0-300°C is a mere 33.9 x 10-7 per ° C"
Scientifically you need to say 33.9*10^-7 WHAT per degree C, presumably not light years or furlongs. Come on get with it :)
The unit is /degC, as indicated in the article and your post.
I was astonished to see 33.9 * 10^-7 when the usual notation would be 3.39 * 10^-6.
Especially since 10^-6 is a conventional point of reference usually denoted by 'micro'.
As to the 'What' per degree C, it is just a proportion of the length (or volume for liquids), which in this case is specified for not just one temperature (usually 20C) but the whole 0-300C range.
Some comparisons for other materials here - https://secure.wikimedia.org/wikipedia/simple/wiki/Coefficient_of_thermal_expansion
Wow, way to display ignorance
The units are correct, in order to determine the length that a specific item grows you multiply by the length of the item which itself has units.
See for example en.wikipedia.org/coefficient_of_expansion
Time for a lesson
That silly little number is a coefficient, that means it has no units! A metre length of glass will inrease in size by 3.39 micro-metres for each degree c of temperature rise
It's been a few years since I did A-level physics...
> Scientifically you need to say 33.9*10^-7 WHAT per degree C
...But I seem to remember thermal expansion coefficients being fractional changes, and thus dimensionless...
[Who's going off to check, just in case he's just made a total arse of himself. Again.]
It's a coefficient, it has no unit. Scientifically.
Or better 3.39 x 10^-6 WHAT per degree C
Dimensionless, old chap
It's a percentage change in each linear dimension. It gets 0.00000339% bigger with every degree of warming.
Thermal expansivity has no units, as it is basically a percentage. http://en.wikipedia.org/wiki/Thermal_expansion
No units because it's a proportional increase. It increases it's dimensions by 33.9*10^-7 metres per metre of length per degree. Mteres per metre cancels, leaving just per degree
Coefficient, not unit
It's a coefficient, not a unit. You could determine it experimentally by measuring the length (or volume) of a piece of the material at one temperature, and then again at another temperature, and then divide the two measurements. Because you are dividing the same units the resulting ratio has no units. If you then divide it by the temperature difference you get the coefficient, whose unit is "per degree C". Hence "33.9 * 10^-7 / degree C".
It's a ratio. Ratios don't have units.
Linguine, mate, Linguine. Don't forget where you are.
If I may divert the conversation slightly:
While I'm here: "Panini" = "Sandwiches", not "Sandwich". The singular form is "Panino".
Every time I pass some pretentious café or glorified sandwich shop in England and see "panini" used as a singular noun, I want to beat someone repeatedly over the head with a copy of "Il Ragazzini". It's not _that_ hard to look something up in a dictionary. Or even to ask a translator (or, hell, even someone who's bilingual!)
Then again, I twitch every time I see a grocer's apostrophe, so maybe I should get out more.
Standard units please
light years? furlongs? Please use standard El Reg units. Bulgarian funbags or somesuch.
@salerio, errm no.
There is no "WHAT" required, this is a coefficient, it works in any system of units.
(Saying miles per mile per degree Celsius, or metres per metre is redundant.)
However, the author did fail to tell us whether this was a linear, area or volume coefficient, but I'd guess that this is its linear coefficient of expansion, judging by it's size.
Always metres by default.
There is no WHAT.
The value stated is the <em>fractional</em> expansion per unit of temperature change.
In other words, if you've got a piece of this glass as long as almost 295,000 Bulgarian airbags all lined up, this glass will change its length by one airbag per degree celsius change.
Come on, El Reg. How hard is to to put a link on a webpage?
... the version marketed with "Energy, style, and enthusiasm" - Lotus Elan
Then the one that does it's job a bit better that the original - Lotus Excel
Then the on that's so thin it's a ghost of the first version - Lotus Esprit
Then the one for iPhone only - Lotus Elite
Any resemblance to Lotus Cars is purely coincidental, unless they actually use this stuff in the new Lotus Esprit, over the engine bay to show off the nice new V8. Or possibly in houses in Évora...
Isn't CTE a ratio so
mm per (mm per degree) simplifies out to per degree?
Will they be able to fit it to the camera on a phone as well.
It's great having a scratch free scree on a phone, but when you turn it around and realise the rear camera has been ruined it's kind of annoying.
If it's a coefficient, it's unitless
(Not UNIT-less as we all are without The Brigadier around these days)
No, they don't need to say WHAT per degree C, thermal expansion is just a ratio.
How much it expands depends on how much you've got.
If you're being pedantic, it's 33.9 x 10-7 metres per metre per ° C
If you're being really pedantic the metres cancel out and leave you with 33.9 x 10-7 per ° C
So, yes, light years or furlongs would be fine. As would linguini. If you want linguini per furlong per ° C then the number itself is going to change though.
There is fail, Salerio, and it's yours.
You may, or may not, wish to rethink your comment.
Sorry, it's you that's wrong this time ...
The units of the coefficient of thermal expansion are length per length per Kelvin - therefore just per Kelvin (or per degree C, if you prefer). This one means that per degree C it expands by 3.4 millionths (of its original size). Not quite sure why this was expressed with the exponent -7 though.
It's a ratio...
..so it's dimensionless.
I thought I'd repeat it too, seems everyone else has.
Is it from Norfolk?
With the rest of Lotus products.
(I know that the Russelheim and Linwood ones were only finished there)
Given that Lotus Group vs Lotus Motorsport Vs Team Lotus vs Lotus F1 are still battling it out over the name "Lotus", does anyone really want to bring a product to market right now which includes "Lotus" in the title?
Bounty - not Lotus.
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