What radiates more heat, white or black?

  • Thread starter ShawnD
  • Start date

ShawnD

Science Advisor
658
1
If I have 2 objects that are the same is every way except for the color, which object will radiate heat faster; the black or the white?
 

FZ+

1,550
2
Black.
 
1,488
20
FZ is right as the question is worded. However, it depends on if the surrounding space is warmer or colder. If it's warmer it will be absorbing heat faster.
 

jimmy p

Gold Member
347
30
well i have never heard of white body radiation...
 

Integral

Staff Emeritus
Science Advisor
Gold Member
7,185
55
It really is not that easy of a question to answer. Color is not specifically a factor in any thermodynamics relationship. What is a factor is surface emissivity. If the bodies are the same in every way the temperature of the 2 bodies will only be different the emissivity has changed. (This may well happen)
 

russ_watters

Mentor
18,834
5,019
Originally posted by Artman
FZ is right as the question is worded. However, it depends on if the surrounding space is warmer or colder. If it's warmer it will be absorbing heat faster.
Faster than what? The question wasn't whether it would absorb or emit, but which would emit more: Black. The way the equations work, you can consider an object to be simultaneously absorbing and emitting radiation.
 

ShawnD

Science Advisor
658
1
Ok now is there a reason for why black emits more? I mean like a real reason not just a vague logical explanation.
 

Integral

Staff Emeritus
Science Advisor
Gold Member
7,185
55
Black tends to adsorp a wider band of energy then lighter colors which reflect more, thus black surfaces can be warmer then light. There is much more then just color involved, so this is pretty much a generaliztion which may not be true in every case.
 
1,488
20
Originally posted by russ_watters
...The question wasn't whether it would absorb or emit, but which would emit more: Black. The way the equations work, you can consider an object to be simultaneously absorbing and emitting radiation.
He also said radiate HEAT faster. If the space around them is colder than the two objects, which will radiate heat faster? The energy emitted may not be in the form of heat.
 

ShawnD

Science Advisor
658
1
Actually the surroundings make no difference. Let's say you have 2 objects, one of them black and one of them not black and both are gaining more heat than they are emiting. The black object will radiate more heat as well as absorb more heat.
 

Related Threads for: What radiates more heat, white or black?

Replies
3
Views
1K
  • Posted
Replies
2
Views
2K
  • Posted
Replies
4
Views
754
  • Posted
Replies
3
Views
3K
Replies
7
Views
49K
Replies
13
Views
8K
  • Posted
Replies
19
Views
6K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top