Is white surface a good radiation emitter?

In summary, the experiment used a radiation cube that can be heated and detected infrared radiation. The results showed that black and white surfaces have very similar levels of radiation, despite common belief that white surfaces are poor absorbers. This is because our eyes can only sense visible light and not infrared, so the effectiveness of absorbers and reflectors in the infrared range cannot be determined by their appearance. Further measurement is needed to accurately determine the absorption capabilities of different surfaces in the infrared spectrum.
  • #1
tkm2002
8
0
In general, a good absorbers of radiation are also good emitters.
In commonsense, something that is should be a poor absorbers.
For example, we dress a white shirt in summer.

However, a experiment has done and shown that the radiation detected of black and white surface are very very close.For example,if the radiation detected of black surface is 14.9, the white surface is 14.7. What is reason about this phenomenon?

The experiment was used TD-8564A Radiation Cube that can be heated from room temperature to approximately 120 oC and the radiation detected is infrared.
 
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  • #2
Hi tkm-
"black" and "white" usually relate to the visual response light intensity. IR radiation from a warm surface, white or black, is a much longer wavelength,
Bob S.
 
  • #3
I would say I'm surprised at this. I have seen pictures of a metal surface with rough patches and black tape taken with an infrared camera and the rough patches appear a bit 'hotter' and the black tape appears a lot hotter.

What were the units of measurement and what frequency is this at? Also what are the 'surfaces' made of?
 
  • #4
The problem is that our eyes only sense the visible light while a lot of the heat that we feel is in the infrared. So just because we see an object as white or black has no real bearing on their effectiveness of an absorber or reflector in spectrums that lie outside the visible range. It would not surprise me though that since the infrared range is right below the visible range that visible light absorption may be indicative of the infrared absorption. But this is not something that we can assume to be valid without further measurement, as you demonstrate in your OP.
 

1. Is a white surface a good radiation emitter?

The answer to this question is not a simple yes or no. The radiation emission capabilities of a white surface depend on various factors such as its composition, texture, and temperature.

2. What factors affect the radiation emission of a white surface?

As mentioned earlier, the composition, texture, and temperature of a white surface can affect its radiation emission. Additionally, the wavelength of the radiation and the surrounding environment can also play a role.

3. How does the composition of a white surface affect its radiation emission?

The composition of a white surface determines how much of the incoming radiation is absorbed or reflected. Some materials, such as metals, are good reflectors of radiation, while others, such as carbon-based materials, are good absorbers.

4. Can a white surface absorb radiation?

Yes, a white surface can absorb radiation. However, the amount of absorption depends on the composition of the surface and the wavelength of the radiation. White surfaces typically have a high albedo, meaning they reflect a large portion of the radiation that hits them.

5. Does the temperature of a white surface affect its radiation emission?

Yes, the temperature of a white surface can affect its radiation emission. According to the Stefan-Boltzmann law, the amount of radiation emitted by an object is directly proportional to its temperature. So, a hotter white surface will emit more radiation than a cooler one.

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