Do Black Macbooks Retain More Heat Than White?

WarHamster40k

macrumors newbie
Original poster
May 24, 2006
3
0
I haven't had a chance to take a decent look at either firsthand, but one of the things that I'm concerned about: since black tends to absorb heat, while white tends to reflect it, might this mean that the black MacBooks are more likely to run hotter than the white or silver Apple laptops? I've been looking at them for a while, but with the current MacBook (Pro) laptops running warm, I was concerned about how much warmer the different cases would make the computer.
 

kgarner

macrumors 68000
Jan 28, 2004
1,512
0
Utah
If I remember my Physics right, the principles of Black Body Radiation say that balck not only absorbs quicker, but releases quicker as well. I.e. A white object will take longer to heat up, but it will also take longer to cool down when heated. A black object will heat up quickly and then release that energy quickly as well.

But, I am not a physicist and it has been many years since I took the class.
 

Totty

macrumors member
Apr 27, 2006
84
0
I'm pretty sure that doesn't work with heat...more with heat created by the sun's rays. That's why you should wear a lighter shirt outside, etc.

heh, kgarner busted out some physics on us while i was typing...trust that opinion more than mine. :)
 

WarHamster40k

macrumors newbie
Original poster
May 24, 2006
3
0
Thanks for the feedback, folks. I'll probably be heading to an Apple store in a week or so, which will give me a chance to debate between the Macbook and Macbook Pro (transitioning from Powerbook 1.5GHz with 512MB ram).
 

savar

macrumors 68000
Jun 6, 2003
1,952
0
District of Columbia
WarHamster40k said:
might this mean that the black MacBooks are more likely to run hotter than the white or silver Apple laptops?
Only if you're leaving it in the sunlight. The color itself has nothing to do with heat *retention*.
 

savar

macrumors 68000
Jun 6, 2003
1,952
0
District of Columbia
kgarner said:
If I remember my Physics right, the principles of Black Body Radiation say that balck not only absorbs quicker, but releases quicker as well. I.e. A white object will take longer to heat up, but it will also take longer to cool down when heated. A black object will heat up quickly and then release that energy quickly as well.

But, I am not a physicist and it has been many years since I took the class.
Umm, No.

http://en.wikipedia.org/wiki/Blackbody
 

Rend It

macrumors 6502
Oct 27, 2003
265
5
United States
kgarner said:
Shhh...don't tell everyone. I was trying to sound smart and stuff. ;) Guess I should have checked the ol' Wikipedia first. :D
Actually, I am a physicist, and kgarner is technically correct. The quantity you should all be looking for is *emissivity*. The derivation of the blackbody law assumes equilibrium, which means the composite system isn't changing certain properties (e.g., temperature). If a body is in thermal equilibrium, it must radiate as much heat as it absorbs (otherwise it would be warming up or cooling down). In either case (absorption or emission), the RATE at which heat is transferred depends on the area, the temperature, and the emissivity. You can look it up, but I would bet that the matte black finish will have a higher emissivity than the glossy white finish.

However (and this is the most important thing), thermal transfer due to radiation goes as T^4, so it really only matters when the radiation is coming from somewhere really hot (like the sun). If your laptop is inside your room, it won't matter which color you have. What will matter is if the thermal paste inside your MB was properly applied. :D

-RendIt
 

kgarner

macrumors 68000
Jan 28, 2004
1,512
0
Utah
Rend It said:
Actually, I am a physicist, and kgarner is technically correct. The quantity you should all be looking for is *emissivity*. The derivation of the blackbody law assumes equilibrium, which means the composite system isn't changing certain properties (e.g., temperature). If a body is in thermal equilibrium, it must radiate as much heat as it absorbs (otherwise it would be warming up or cooling down). In either case (absorption or emission), the RATE at which heat is transferred depends on the area, the temperature, and the emissivity. You can look it up, but I would bet that the matte black finish will have a higher emissivity than the glossy white finish.

However (and this is the most important thing), thermal transfer due to radiation goes as T^4, so it really only matters when the radiation is coming from somewhere really hot (like the sun). If your laptop is inside your room, it won't matter which color you have. What will matter is if the thermal paste inside your MB was properly applied. :D

-RendIt
Ummm...yeah...that's what I meant. ;) Glad I rememberred something form those classes even if I can't explain it right. :D
 

wPod

macrumors 68000
Aug 19, 2003
1,654
0
Denver, CO
Rend It said:
Actually, I am a physicist, and kgarner is technically correct. The quantity you should all be looking for is *emissivity*.

...

If your laptop is inside your room, it won't matter which color you have. What will matter is if the thermal paste inside your MB was properly applied. :D

-RendIt
Thank you. I was about to yell at some people for getting that wrong! heh. im not a physicist, but i am a mechanical engineer and deal a lot with heat transfer. And I agree with RendIt. . . just keep your laptop inside and youll be fine. If you leave a black MB and a white MB in a car in the sun light (especially in TX where i am) then the black MB will deffinitly get hotter. with apple's reccomended storage and operating temperatures being 113 deg F and 95 deg F respectivly, I would not suggest trying this out because in the summer, the temperature inside a car sitting in direct sun light can easily hit 130 deg F or more! so basicly in the worst case they will both be fried! so just be nice to your MB and it will be nice to you. . . whatever color it is, cause all colors are equal, as long as they are made by apple! lol
 

Stratification

macrumors regular
Jan 17, 2005
240
0
Spokane, WA
Thanks for everyone bringing this out. It's been driving me nuts seeing all the posts various places speculating that black would be hotter. The difference between radiant and conducted heat apparently escapes a lot of people.