Behaviour of photons in a 'sealed room'

  • Thread starter NeilWallace
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In summary, when the light switch is off, the room becomes dark because there are no orange photons in the room. These orange photons go to where they are not absorbed, which is the hand mirror. If you put a hand mirror in a room and turn on the light, the room will be brightly lit for a few seconds because the hand mirror will reflect all the photons back to the light bulb.
  • #1
NeilWallace
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Hi could some one help me understand the relationship between photons and a sealed room to which no photons can escape. Say there is a light bulb in the room producing photons that are all the visible spectrum and the wall paper is made of beta carotine from carrots so some of the photons are absorbed and the orange ones are emitted.

Why is it when the light switch is turned off it all goes dark and does not give an orange light to the room as there are only orange photons in the room. Where do these orange photons go?

Im just starting on this so its probably a crazy question..!
 
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  • #2
Welcome to PF!

Hi Neil! Welcome to PF! :smile:
NeilWallace said:
Why is it when the light switch is turned off it all goes dark and does not give an orange light to the room as there are only orange photons in the room. Where do these orange photons go?

They do keep going when the light is switched off …

but every time they bounce off a wall, they run a risk of being absorbed :redface:

in say 0.1 seconds, for a standard-sized room, they bounce so many times that they're virtually all absorbed! :biggrin:
 
  • #3
Thanks. But say the wall is coated in something that will not absorb these orange wavelength photons. I thought that the idea was that materials only absorb certain wavelengths of photons and kind of chuck back photons that it cannot absorb - and this is what gives things their colour.

Is this not true? I had in mind some kind of 'vacuum flask' that would store light indefinetly because the photons were of a wavelength that could not be absorbed by the material.
 
  • #4
NeilWallace said:
I had in mind some kind of 'vacuum flask' that would store light indefinetly because the photons were of a wavelength that could not be absorbed by the material.

Well, a perfect mirror should do that.

But I don't know how perfectly reflective a mirror can be.
 
  • #5
Oh ok like a fibre optic cable. so if you packed this mirror lined flask full of photons it would be like a light store for use at a later date as a torch. Not sure what maximum photon density you can get in a space is. Thanks.
 
  • #6
There's no limit to the number of photons that can occupy the same space (or if there is, it is not about to be achieved in currents labs), but even if you have 99.9999% reflection, light won't last a second in a hand-sized flask (and adding extra decimals is exponentially difficult).
 
  • #7
Dr lots o watts is right.

But if you could somehow do it, the box would be getting filled with more and more yellow light. It would eventually get so much yellow light in it that it would destroy the lamp by burning it up.

If you could do it with an indestructible lamp, it would eventually get so bright inside with yellow light that you would be instantly killed by it the moment you opened the door.
 
  • #8
Dear NeilWallace I understand what you say but just read this - matter is condensed,passive,inertial or lazy :-) form of energy and light is energy.
Why don't you employ pair annihilation to get high frequency light.
 
  • #9
'pair annihilation..' I'd have to look into that as I don't understand it and figure its not something you can try at home.. :)

I think I understand the limitations of the light store in a flask idea without a 100% reflective surface it would not work and 100% reflective surfaces do not appear to exist.

I thought if you switched the light on in the flask for 10 minutes and had some sort of valve that limited the number of photons that could leave the flask to be the same rate of photon emission of the light bulb then theoretically you would have 10 minutes of light to light the room at a later date.

I think Ill stick to energy saving light bulbs.. :)
 
  • #10
Ha!Ha! :-)) Yeah! NeilVallace its really tough for performing Pair annihilation at home.I've to shell out billions of dollar and spend terawatts of energy just to get mere 1 kJ of energy from the experiment.The idea of power saving CFL is better. :-))
 

1. How do photons behave in a sealed room?

When photons are in a sealed room, they behave the same way they do in any other environment. They travel at the speed of light, can be absorbed or reflected by materials, and can interact with each other through phenomena such as interference and polarization.

2. Can photons be trapped in a sealed room?

Technically, photons cannot be completely trapped in a sealed room. This is because they have no mass and are constantly moving at the speed of light. However, they can be contained and reflected within a sealed room for a period of time depending on the materials and design of the room.

3. How does the material of the room affect the behavior of photons?

The material of the room can greatly affect the behavior of photons. Materials with high reflectivity, such as mirrors, can cause photons to bounce around and create a higher energy density. Materials with low reflectivity, such as black surfaces, can absorb photons and create a lower energy density.

4. Do photons lose energy in a sealed room?

Photons do not lose energy in a sealed room unless they are absorbed or reflected by materials in the room. As long as the photons continue to reflect off of surfaces without being absorbed, their energy will remain constant.

5. Can photons escape a sealed room?

In theory, photons cannot escape a sealed room as they have no mass and are constantly traveling at the speed of light. However, if the room is not perfectly sealed or if there are small openings, some photons may be able to escape through these openings.

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