Why Doesn't My Homemade Nitrogen Tube Light Up in the Microwave?

[cragar]

I remember seeing a physicist on TV putting an argon or nitrogen sealed glass tube in a microwave and when he turned it on the tube started flashing an emitting visible light,
So how come when i put a sealed glass jar that i glued a lexan lid on in the microwave it does not emit light , i realize that the air in the jar is a mixture of gases , there is probably something fundamental i am missing .

 

[cjameshuff]

I remember seeing a physicist on TV putting an argon or nitrogen sealed glass tube in a microwave and when he turned it on the tube started flashing an emitting visible light,
So how come when i put a sealed glass jar that i glued a lexan lid on in the microwave it does not emit light , i realize that the air in the jar is a mixture of gases , there is probably something fundamental i am missing .

The factor you're missing is pressure:
http://en.wikipedia.org/wiki/Paschen's_law

 

[turbo]

The tubes are filled with low-pressure argon or neon in an otherwise evacuated tube.

 

[cragar]

Thanks for the answers ,
so if i evacuated some of the air in the tube , and reduced the pressure would it emit light .

 

[sardar]

It is interesting to see the different reactions of different gases in a microwave. The physicist you saw on TV was most likely using a nitrogen tube to demonstrate a principle called "dielectric breakdown." This occurs when the electric field inside the tube becomes strong enough to cause the nitrogen molecules to break apart, releasing energy in the form of light. This phenomenon is similar to what happens in a neon light or a plasma globe.

When you put a sealed glass jar with a lexan lid in the microwave, the air inside is a mixture of gases, as you mentioned. This mixture may not have the same dielectric properties as pure nitrogen, so the electric field inside the jar may not be strong enough to cause dielectric breakdown and emit light. Additionally, the presence of the lexan lid may also affect the electric field and prevent dielectric breakdown.

It is important to note that microwaves are not meant to be used as a laboratory tool and can be dangerous if not used properly. I would not recommend trying to replicate this experiment at home. As a scientist, it is always important to understand the underlying principles and limitations of any experiment before attempting to replicate it.