Exploring Black & White Materials: Absorption vs. Reflection

[theobromine]

True black materials theoretically absorbs all wavelengths of visible light. True white materials reflect all wavelengths of light.

If a material which was black at room temperature was heated up to incandescence so that it was emitting all visible wavelengths (white light), and then light was shone at the material, would it:

a) Absorb all light, as it was black when not incandescent
or
b) Reflect all light, in essence behaving as a white object

Insight would be much appreciated!

 

[jbriggs444]

https://en.wikipedia.org/wiki/Black_body

 

[Dale]

Summary: True black materials theoretically absorbs all wavelengths of visible light. True white materials reflect all wavelengths of light.

What happens when a material which is ordinarily black is heated to incandescent?

If a material which was black at room temperature was heated up to incandescence so that it was emitting all visible wavelengths (white light), and then light was shone at the material, would it:

a) Absorb all light, as it was black when not incandescent

It still absorbs all light. If you shine a flashlight on the sun it does not reflect off the sun. It is brighter than your flashlight because it emits more light to the flashlight than it absorbs from the flashlight, but it does not reflect or scatter your flashlight.

 

[theobromine]

It still absorbs all light. If you shine a flashlight on the sun it does not reflect off the sun. It is brighter than your flashlight because it emits more light to the flashlight than it absorbs from the flashlight, but it does not reflect or scatter your flashlight.

Thanks, that's helpful.

 

[Dr_Nate]

If you shine a flashlight on the sun it does not reflect off the sun. It is brighter than your flashlight because it emits more light to the flashlight than it absorbs from the flashlight, but it does not reflect or scatter your flashlight.

Just a little correction: this statement is not really accurate because the sun is not a perfect blackbody. It is true if we replace the word sun with perfect blackbody at several thousand Kelvin.