Does the color of an object change as it gets hotter?

In summary: So, very hot objects would appear bluish-white due to the intensity of blue light being higher, but at closer distances, it would appear white due to the saturation of all wavelengths in the eye. In summary, as temperature increases, the intensity of radiation shifts to the left in the electromagnetic spectrum, with the peak eventually falling into the invisible portion. However, the behavior of the curve remains consistent for any temperature, with the hotter the object, the brighter it glows in the visible range. This makes very hot objects appear bluish-white due to the higher intensity of blue light, but at closer distances, they may appear white due to the saturation of all wavelengths in the eye.
  • #1
APUGYael
41
1
screen-shot-2013-10-29-at-22-32-24.png

I'm talking hotter than T = 6000k.
The higher the temperature, the more the curve in the attached figure would shift to the left (while at the same time getting higher).

So the intensity peak would eventually fall back into the invisible portion (very small wavelength this time) of the electromagnetic spectrum. (UV and beyond)

You would still see visible light though, right? Just as you could still detect infrared radiation.
Is this always the case? Or can an object be so hot that it just doesn't radiate any visible light?

Me, personally, I don't think so. But I figured it'd be an interesting question to ask. Tried googling it. Couldn't find an answer relatively quickly.

-Yael
 

Attachments

  • screen-shot-2013-10-29-at-22-32-24.png
    screen-shot-2013-10-29-at-22-32-24.png
    28.5 KB · Views: 546
  • screen-shot-2013-10-29-at-22-32-24.png
    screen-shot-2013-10-29-at-22-32-24.png
    28.5 KB · Views: 881
Last edited:
Physics news on Phys.org
  • #2
Hi APUGYael:

Do you see in the chart that for higher temperatures, a greater amount of power occurs in the visual part of the spectrum than for lower temperatures. The fact that the peak of the radiation is outside of the visual range, does not change this.

Regards,
Buzz
 
  • #3
Buzz Bloom said:
Hi APUGYael:

Do you see in the chart that for higher temperatures, a greater amount of power occurs in the visual part of the spectrum than for lower temperatures. The fact that the peak of the radiation is outside of the visual range, does not change this.

Regards,
Buzz

Exactly what I figured. Sorry, I might've been unclear. What I am asking is if the curve radically changes behaviour at a certain (high) temperature.
 
  • #4
Here is an illustration of what @Buzz Bloom is saying. The vertical grey lines mark the visible range and the temperature is T = 20,000 K.

BB.png
 

Attachments

  • BB.png
    BB.png
    6.2 KB · Views: 959
  • Like
Likes OmCheeto
  • #5
APUGYael said:
Exactly what I figured. Sorry, I might've been unclear. What I am asking is if the curve radically changes behaviour at a certain (high) temperature.

No, the behavior remains consistent for any temperature. The hotter the object becomes, the brighter it glows in the visible range.
 
  • Like
Likes APUGYael
  • #6
kuruman said:
Here is an illustration of what @Buzz Bloom is saying. The vertical grey lines mark the visible range and the temperature is T = 20,000 K.

View attachment 224083

Yeah, I know what you're/he is saying. That's what I was talking about in my original post.
"The higher the temperature, the more the curve in the attached figure would shift to the left (while at the same time getting higher)."
i.e. the peak shifts up and to the left, so that all forms of electromagnetic radiation also become more intense (read: also move up)

I'm asking if there's a certain temperate where this behaviour is no longer valid.
 
  • #7
APUGYael said:
I'm asking if there's a certain temperate where this behaviour is no longer valid.
Hi APUGYael:

Answer to the question quoted above.
NO.

Regards,
Buzz
 
  • #8
Drakkith said:
No, the behavior remains consistent for any temperature. The hotter the object becomes, the brighter it glows in the visible range.

Would very hot objects be white or blue?

White would be understandable because all wavelengths of visible light are emitted, but blue would always have higher intensity on the chart (for high temperatures).
Would objects then look blue, but looking at them would look like looking at the sun (white light entering eye)?
 
  • #9
APUGYael said:
Would very hot objects be white or blue?

According to a spectral radiation calculator I found, at 100,000 K there is roughly 5x more power in the blueish end of the visible spectrum than in the red end. This is also the case for 50,000 K and 10,000 K. I assume the pattern holds for temperatures higher than 100,000 K, but the calculator does not go that high. This would probably make very hot objects look bluish-white unless you were close enough that your eyes are saturated at all wavelengths, in which case it would just look blindingly white.
 
  • Like
Likes APUGYael
  • #10
Drakkith said:
According to a spectral radiation calculator I found, at 100,000 K there is roughly 5x more power in the blueish end of the visible spectrum than in the red end. This is also the case for 50,000 K and 10,000 K. I assume the pattern holds for temperatures higher than 100,000 K, but the calculator does not go that high. This would probably make very hot objects look bluish-white unless you were close enough that your eyes are saturated at all wavelengths, in which case it would just look blindingly white.

I did the calculations up to 6 trillion Kelvin, and the pattern holds for higher temperatures.

visible.temp.output.curves.png
 

Attachments

  • visible.temp.output.curves.png
    visible.temp.output.curves.png
    5.4 KB · Views: 468

1. Do all hot objects glow?

No, not all hot objects glow. Only objects that reach a high enough temperature will emit visible light, which is what we perceive as glowing.

2. Why do hot objects glow?

Hot objects glow because of a process called thermal radiation. As the object's temperature increases, the particles in the object vibrate faster, emitting electromagnetic radiation in the form of visible light.

3. At what temperature do objects start to glow?

Objects typically start to glow at temperatures around 798 degrees Fahrenheit (426 degrees Celsius). This temperature is known as the red heat or red heat limit.

4. Can objects glow without being hot?

Yes, objects can glow without being hot. This is because some materials can absorb light and re-emit it at a longer wavelength, which makes them appear to be glowing. This is known as phosphorescence or fluorescence.

5. Can objects glow in colors other than red, orange, and yellow?

Yes, objects can glow in a variety of colors depending on their temperature. As the temperature of an object increases, the color of its glow changes from red to orange, yellow, white, and eventually blue. This is due to the different wavelengths of light emitted at different temperatures.

Similar threads

  • Other Physics Topics
Replies
16
Views
4K
  • Other Physics Topics
Replies
19
Views
16K
Replies
6
Views
2K
  • Introductory Physics Homework Help
Replies
19
Views
919
  • Other Physics Topics
Replies
8
Views
1K
Replies
29
Views
2K
  • Thermodynamics
Replies
20
Views
9K
  • Thermodynamics
Replies
8
Views
1K
Replies
4
Views
1K
  • Astronomy and Astrophysics
Replies
13
Views
3K
Back
Top