Cathode Ray Tube - Help Needed (1 Viewer)

[skoe]

Well! On doing a recent experiment in class, no one (Including the Teacher) could determine what caused the colours of the Cathode Ray...

What determines the Colour?

 

[rumour]

the fluorerescent paint, perhaps.................

 

[t-i-m-m-y]

Originally posted by skoe
Well! On doing a recent experiment in class, no one (Including the Teacher) could determine what caused the colours of the Cathode Ray...

What determines the Colour?

i think it could possibly be due to the emission of energy residing in different parts of the electromagnetic spectrum

 

[Xayma]

Its the gas that is inside it, and its due to what t-i-m-m-y said.

 

[xiao1985]

i think it's the excitation of the electrons around the air molecules inside the cathode ray tube... when they drop down they emit emr... some in visible range... when the pressure is lowered to a certain level, collision is no longer much possible, therefore, when electrons collide with the fluoresence material at the end to excite the electrons to the next shell... when they drop down, they emit emr... soem in visible range...

 

[rumour]

sorry for my earlier quite stupid comment, but we did it @ school today & the teacher said it was due to:
the sudden deceleration of a charged particle, releasing energy in the form of light!

 

[Xayma]

Im sure the gas has something to do with it as different noble gases produce different colours when in them.

 

[George W. Bush]

Well the colour of the light is obviously affected by the wavelength
and the energy is released by the slowing elections

 

[The Bograt]

If you mean the cathode ray tube (discharge tube) then the colour is determined by the gas and the pressure. If you mean the Crookes tube with the paddle wheel then yes, obviously it is as rumour said the fluorescent paint

 

[BFEPNS]

soooo different gas = different colour???

 

[Xayma]

Yep,

Thats how different colour "neons" are produced by using things like Xeon, Neon, Argon, Krypton etc.

 

[redslert]

errrr i don't think it is gas causing the colours

because the cathode ray tubes are vaccums....so yeh there's like no gas inside

colours are already explained by xiao1985

 

[t-i-m-m-y]

lol. i don't get the flourescent paint bit. what paint did we paint on?

 

[Xayma]

Originally posted by redslert
errrr i don't think it is gas causing the colours

because the cathode ray tubes are vaccums....so yeh there's like no gas inside

colours are already explained by xiao1985

But those colours are formed by the gases electrons jumping energy level. Very low pressure tubes have no visible light. The gas that is inside them, determines how far they jump energy level (eg Cl's electrons are held closer then Na's) and hence the wavelength of light emitted.

 

[redslert]

but it's a vacuum?!
how can you have something in nothing?

 

[t-i-m-m-y]

Originally posted by redslert
but it's a vacuum?!
how can you have something in nothing?

isn't it an 'evacuated tube'. not quite a vacuum

but that second bit was real deep. *ponders

 

[Xayma]

Originally posted by redslert
but it's a vacuum?!
how can you have something in nothing?

It isn't strictly a vacuum just like space isnt a perfect vacuum but for example one of the ones we have at school (which you can barely see the glow) is at 0.005% Atmospheres.

 

[xiao1985]

Originally posted by redslert
errrr i don't think it is gas causing the colours

because the cathode ray tubes are vaccums....so yeh there's like no gas inside

colours are already explained by xiao1985

ops.. guess i should explain it in better words... i meant when electron collides with atoms (eventually it will), the electron will decelerate and transform its energy to the atom, and hence excite the electrons around the nucleus to a higher atomic orbital. how ever, the electrons at a higher energy level is not stable... when it (electrons in an atom or molecule) drops back down, it emits excessive energy in the form of emr of some sort... those emitted in visible is observed by naked eyes...

 

[Xayma]

Hmm theoretically would it be possible to get a super heavy atom (ie undiscovered yet) whose electrons would emit non-visible EM radiation?

 

[t-i-m-m-y]

Originally posted by Xayma
It isn't strictly a vacuum just like space isnt a perfect vacuum but for example one of the ones we have at school (which you can barely see the glow) is at 0.005% Atmospheres.

thats what i was thinking. hence 'evacuated' tube may sound less misleading.

about that super heavy atom business: wouldn't the production of x-rays from a tungsten metal be what ur talking about?