What radiates more heat, white or black?

  • Context: High School 
  • Thread starter Thread starter ShawnD
  • Start date Start date
  • Tags Tags
    Heat
Click For Summary

Discussion Overview

The discussion revolves around the question of which color, black or white, radiates heat more effectively when comparing two identical objects differing only in color. The scope includes thermodynamics concepts, emissivity, and the impact of surrounding temperatures on heat radiation.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants assert that black objects radiate heat faster than white objects.
  • Others note that the surrounding temperature influences the rate of heat absorption and emission, suggesting that if the surroundings are warmer, the objects may absorb heat faster.
  • One participant emphasizes that color alone is not a definitive factor in thermodynamics, pointing out that surface emissivity plays a crucial role in heat radiation.
  • There is a discussion about the reasons behind black objects emitting more heat, with some participants mentioning that black surfaces absorb a wider range of energy compared to lighter colors.
  • Another participant questions the implications of surrounding temperatures, suggesting that the energy emitted may not necessarily be in the form of heat.
  • One participant argues that the surroundings do not affect the black object's ability to radiate heat, stating that it will radiate more heat regardless of the surrounding conditions.

Areas of Agreement / Disagreement

Participants express differing views on the influence of color and surrounding temperatures on heat radiation, indicating that there is no consensus on the matter. Multiple competing perspectives remain unresolved.

Contextual Notes

The discussion highlights the complexity of heat radiation, including factors such as emissivity and the conditions of the surrounding environment, which are not fully resolved within the conversation.

ShawnD
Science Advisor
Messages
715
Reaction score
2
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?
 
Science news on Phys.org
Black.
 
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.
 
well i have never heard of white body radiation...
 
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)
 
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.
 
Ok now is there a reason for why black emits more? I mean like a real reason not just a vague logical explanation.
 
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.
 
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.
 
  • #10
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.
 

Similar threads

High School Heat and Infrared radiated from an object
  • · Replies 12 ·
Replies
12
Views
3K
Undergrad Dark body vs light body and heat emission
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Can a black material reflect light when heated to incandescence?
  • · Replies 4 ·
Replies
4
Views
2K
High School Heat transfer -- Several questions
  • · Replies 6 ·
Replies
6
Views
4K
Graduate EM radiation temperature vs particle temperature
  • · Replies 14 ·
Replies
14
Views
2K
Undergrad Questions about Jean-Rayleigh's derivation of Ultraviolet Catastrophe
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Estimate thickness of an object based on radiative heat flux decay curve
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Equilibrium between objects at different temperatures?
  • · Replies 101 ·
4
Replies
101
Views
9K
Undergrad Expected visible vapor time of boiling water at STP without any heat?
  • · Replies 9 ·
Replies
9
Views
2K
Undergrad Blackbody radiation and the cosmic microwave background
  • · Replies 29 ·
Replies
29
Views
5K