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Registered Member #1667
Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374
Bored Chemist wrote ...
"A candle flame is normally not conductive" Yes it is.
I think many people fail to realise that ions in air are fairly stable, you can blow then around for a few feet with a fan and they take up to a few seconds to recombine.
reminds me of spray discharge experiments with a DST, objects even across the room soon occasionally begin to discharge to a grounded wire nearby.
On-Topic: I assume some of you already know the flame triode video:
ps. dammit, Nah already mentioned the flame triode...
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
Proud Mary wrote ...
Here is a colour chart from which you can estimate the temperature of the glowing blade tip.
The sparks of steel burning in air which we see in the video suggest local temperatures of 1350°C or so.
And if you don't like the results, you can change the colour temperature settings on your monitor until you get the right answer. OK I exaggerate, but I'm sure that you cannot rely on something like that for anything but the roughest estimate. Even the colour chart itself says it should be viewed in daylight, but not direct sunlight ( or artificial light) because that would upset the outcome.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Bored Chemist wrote ...
Proud Mary wrote ...
Here is a colour chart from which you can estimate the temperature of the glowing blade tip.
The sparks of steel burning in air which we see in the video suggest local temperatures of 1350°C or so.
And if you don't like the results, you can change the colour temperature settings on your monitor until you get the right answer. OK I exaggerate, but I'm sure that you cannot rely on something like that for anything but the roughest estimate. Even the colour chart itself says it should be viewed in daylight, but not direct sunlight ( or artificial light) because that would upset the outcome.
In fact, colour is commonly used to make estimates of metal temperature in practical metalwork and smithing, and even a lackadaisical Google search will find similar colour charts and tables based on descriptive terms such as 'salmon' and 'cherry red.' Time and effort can be saved by knowing the degree of accuracy required of a particular measurement, and not needlessly exceeding it for want of anything more useful to contribute to a task.
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
I'm well aware that, with practice, you can judge temperature by eye. I have done it, notably when pointing out that the temperature control on one of the furnaces at work had gone belly up. My comment was something like "That thing's nowhere near 400C; it's so bright you could ****** read by it". What I'm saying is that the process of photographing that chart and sending it electronically to a monitor, the characteristics of which are unknown, adds so many uncontrolled variables that you don't even know how inaccurate it is. That takes you into the realm of unknown unknowns and that's not a good place to be doing science.
Incidentally, if my blood were anything like the colour described on that chart as "blood red" I'd go to see a doctor and the so called "white" is distinctly yellow.
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In-air thermionic emission?
