Measuring software for schools
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There are circuit breakers, yes?
Snort. One would assume so. But that seems likely to cause a scene, so, since I'm not stupid, I wouldn't do it.
Here's another instance. Same high school. I and a friend got drunk in the school parking lot skipping a study hall the period before our Spanish class was due to take a field trip to a local Mexican restaurant. Since I had the presence of mind not to act like an idiot, nobody ever found out. Question: does it matter? Answer: obviously not. But @Rhywden sounds like the kind of person who would freak out and suspend me, call the cops, etc., on principle.
Have a sense of proportion.
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You still don't seem to grasp the notion that I am responsible for your actions while you are in my class.
And since you don't seem to understand this simple concept, I think I'm done arguing with you. One last time: I usually couldn't care less how moronic you act. But as soon as you're in my class, it's my responsibility that no one comes to harm.
And if that means that I have to rule by an iron fist, then so be it. Because for every experiment that is harmless under certain conditions, the same experiment can turn quite dangerous as soon as you change one little detail.*) And I don't expect my pupils to always know the difference. If you had ever stood in front of a class and listened to all that half-knowledge and not-quite-right-information, you'd know that. Never heard of "knows just enough to be dangerous"?
I've seen several times now what happens when one doesn't take security seriously - and I don't intend to be the one who pays for the idiocy of others.
And being drunk on schoolgrounds? You bet your ass you'd be hauled in front of the principal. If you let yourself be caught then you deserve whatever flak you're catching.
*) For instance: The reaction of Lithium with water is an experiment I let my pupils do. Sodium+Water is something only I will demonstrate. And Potassium+Water is something I'm a bit afraid of.
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hauled in front of the princip
lealย - or -
hauled in
front of theon principleFTFY with options
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Fixed
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A drop of solder would be relatively minor.
I dripped solder on my leg some 40 years ago (I was wearing long pants; it went through them1.) I still have the scar from it.
1This was the 70's; the pants were polyester. There was some melting of the fibers involved.
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You still don't seem to grasp the notion that I am responsible for your actions while you are in my class.
You keep talking but all I hear is "wah! wah! wah! My pussy hurts!"
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the pants were polyester. There was some melting of the fibers involved.
Well, aggravating circumstances then.
How much solder? The amount I've been talking about was a small drop. Rhywden seems to think I'm splashing buckets of the stuff.
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On the topic of dangerous experiments, the one physics lab demo that stayed with me from school was a demo showing that glass conducts (via the impurities providing charge-carriers) if you get it hot enough.
For those that haven't seen it done, they simply wrapped copper wire round each end of a glass rod and plugged it into the mains. Then it was heated to red heat with a large bunsen burner. Nothing at all happens until the glass gets juust hot enough then it explodes, violently, as it conducts (and pops the lab circuit breakers).
I hope Health and Safety wouldn't stop that being done these days, exploding red-hot glass is a great learning tool
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How much solder? The amount I've been talking about was a small drop.
One drop. How big? I don't know. Just big enough for gravity to overcome surface tension. I was trying to solder two wires together (on the underside of a model railroad layout). Added enough solder to the joint that a drop dripped directly onto my leg.
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On the topic of dangerous experiments, the one physics lab demo that stayed with me from school was a demo showing that glass conducts (via the impurities providing charge-carriers) if you get it hot enough.
For those that haven't seen it done, they simply wrapped copper wire round each end of a glass rod and plugged it into the mains. Then it was heated to red heat with a large bunsen burner. Nothing at all happens until the glass gets juust hot enough then it explodes, violently, as it conducts (and pops the lab circuit breakers).
I hope Health and Safety wouldn't stop that being done these days, exploding red-hot glass is a great learning tool
I'm not entirely sure why the glass should explode. I did the very same experiment and the glass did just fine.
And the glass does not conduct due to any impurities - it's the normal semiconductor effect which does that. Higher temperature equals lower resistance and all that.
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I'm not entirely sure why the glass should explode.
If the glass becomes the sufficiently conductive, the current through it will cause it to get hotter, further increasing it conductivity, in a positive feedback loop until something breaks. Maybe the glass breaks, maybe it melts, maybe the breaker trips, maybe you remove the bunsen burner before any of those happen; hard to guess which. In your case, I guess one of the latter two.
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the current through it will cause it to get hotter, further increasing it conductivity, in a positive feedback loop
That's what it was explained as. Thermal runaway due to the lack of current limit. It was impressive, a real 'bang'.
And the glass does not conduct due to any impurities - it's the normal semiconductor effect which does that. Higher temperature equals lower resistance and all that.
I had to look that up. Your're right, it's the same mechanism (valence charge-carriers) in ionic things like the Na+ in the molten glass and normal Si doped-semiconductors. I wonder why most references talk about ionic charge flow and semiconductor charge flow like they are two entirely seperate mechanisms?
I still don't think the glass would conduct without the sodium carbonate added though, the Na+ is transporting the charge?
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We both are correct actually ;)
I thought about it some more and your experiment basically consists of a short-circuit while mine has a serially connected 40 W lamp after the glass rod.
The short-circuit then indeed explains the exploding glass. Whereas in my version the resistance doesn't fall under the resistance value of the lamp - it's basically the same reason why you put a resistor in front of an LED.
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I had to look that up. Your're right, it's the same mechanism (valence charge-carriers) in ionic things like the Na+ in the molten glass and normal Si doped-semiconductors. I wonder why most references talk about ionic charge flow and semiconductor charge flow like they are two entirely seperate mechanisms?
I still don't think the glass would conduct without the sodium carbonate added though, the Na+ is transporting the charge?I think even pure SiO2 would conduct under those circumstances - basically the heat is simply pushing enough electrons from the valence band into the conduction band. The presence of other atoms should simply increase the flow - and the type of foreign atoms doesn't matter here, we're not trying to create a diode or something, after all
And the transport of charge happens through the usual way: The electrons go their merry way, now that you pushed them into the conduction band and the positive charges are transported by hole conduction (or "musical chairs") ;)
Don't forget that the glass is not molten. If it was molten you'd have a puddle of glass on the ground - and then you'd really have transport of charge via actual kations and anions wandering around.
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Thank you very much, that makes sense. It would be very interesting to try a pure glass rod (if you can buy such a thing)
I love TDWTF, software, hardware and now physics!
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Well, now I almost have to try the short-circuit variant. I'm not quite sure if it is such a good idea, what with the hot glass flying around - my colleagues might be a bit annoyed if there were tiny beads of glass embedded everywhere.
I mean, I have several fumehoods, but still... damn. Though there is one in the preparation room we're not actually using anymore.
And here I was thinking that "things going boom" was only happening in chemistry! (I was really astounded, by the way, when I discovered that you can get stuff like pure sulfuric and nitric acid over Amazon without any kind of checks at all - I mean, that's basically all you need to make gunpowder cotton or nitroglycerin...)
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stuff like pure sulfuric and nitric acid over Amazon
eBay has someone selling concentrated Hydrofluoric acid, I draw the line before that. The stuff scared the hell out of me when I had to use it, not to mention having to be shown how to use the emergency kit first. I don't want the kind of people that post YouTube comments to have access to that!
hot glass flying around
In our lab demo they just used perspex screens and I don't remember any glass getting where it wasn't wanted.
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Yeah, we also have hydrofluoric acid in our repository and I haven't yet had the nerve to even touch it.
A friend of mine had to spend 4 weeks in the hospital due to accidental exposure to the stuff.
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On the topic of dangerous experiments, the one physics lab demo that stayed with me from school was a demo showing that glass conducts (via the impurities providing charge-carriers) if you get it hot enough.
Cover for our chemistry teacher decided to show the by-product of burning hydrogen.
They didn't leave the reaction producing hydrogen going long enough to flush the system of oxygen.
The resultant explosion resulted in quite a bit of glass being lodged in the ceiling of the lab....
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The resultant explosion resulted in quite a bit of glass being lodged in the ceiling of the lab....
In my freshman year of college i took chem. We had lecture first andthen lab back to back.
the professor walks in and gives the lecture but absolutely no one is paying attention. they're all staring at his right hand and arm, which was absolutely COVERED in scars and missing all but the thumb and half the pinky for fingers.
we found out the story in the lab where there was a square of ceiling that was marked off by a series of rings of paint and had a brown stain. this was directly over the teacher's lab table.
he walks in and points to the ceiling.
I'm sure many of you were wondering what the story is about my arm, well there's the other half of the story. You are playing with the big boys and girls of the chemical world now.
If you mess up there will be consequences, things will get broken, you could very well end up dead or maimed. If you goof off in my class even once I will flunk you and make you leave, because I do not want to have to attend the funeral of one of my students... again.
that's a verbatim quote. i was recording audio of my lectures back then and saved the recording.
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A friend of mine had to spend 4 weeks in the hospital due to accidental exposure to the stuff.
Looks like they got off lightly. HF is where chemistry gets serious.
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We had three incidents during my time at university:
a) Someone was doing an experiment with Sodium and obviously didn't use gloves for cutting the stuff. How do I know that? Because he somehow lodged a tiny piece under his fingernail. Then, when it began to react with the skin moisture he put the finger under the water tap. But the idiocy didn't end there, oh no! He remembered that Sodium reacts violently with water and thusly thought that it would be better to let only a dribble of water flow over the finger...b) Another guy had a gas cylinder full of Nitrogen in his room (without windows). The thing was either leaking or he didn't close it properly and it promptly and slowly filled the room with Nitrogen. This was on a friday evening and they found him monday morning, partially frozen.
c) Someone put too many open containers with solvents under a fume hood which simply couldn't get rid of the emerging gasses fast enough. Then a little spark - and bam! One seriously injured student and about 1,000,000โฌ worth of damages.
Looks like they got off lightly. HF is where chemistry gets serious.
Yeah. A palm-sized exposure means certain death. And horrible pain in the hours before, to boot.
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Yes, I'd like that too. I'd like free money, but sadly no dice.
You don't need dice. What you need is a large bank of industrial printers.
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did someone say dice?
@sockbot 5d4 6d8 1d10 1d100
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Rolling 5d4: 2, 2, 1, 4, 3 Sum: 12
Rolling 6d8: 2, 1, 2, 7, 3, 4 Sum: 19
Rolling 1d10: 9 Sum: 9
Rolling 1d100: 12 Sum: 12
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Those rolls are awful.
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Good thing @sockbot isn't a baker.
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Rolling 2d6: 4, 6 Sum: 10
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I think that's a bug.
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Rolling 2d6: 1, 6 Sum: 7
Rolling 1d6: 3 Sum: 3
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Yeah, except @aliceif didn't dice anything and sockbot rolled for her.
Nm, apparently I just quote replied on the wrong post. There is an html comment there.
Whatever.
@sockbot, roll 3d8
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Rolling 3d8: 5, 2, 7 Sum: 14
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Yeah, except @aliceif didn't dice anything
Good thing @sockbot <!--โ2d6--> isn't a baker.EDIT: Hanzoโd, again
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We could have some fun with thisโฆ
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Rolling 10d10: 2, 10, 3, 3, 8, 1, 6, 4, 7, 8 Sum: 52
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hidden mentions through the use of <small> tags.
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And then Hanzoed out.
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yes, but i saw, sockbot is still echoing the input that triggers dice rolls so i can debug. :-D
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Yeah. A palm-sized exposure means certain death. And horrible pain in the hours before, to boot.
Yeah, HF is on my list of "don't screw with this" chemistry, as well as on my list of "what should a poison-gas spell generate?"
Filed under: can you buy a ton cylinder of chlorine trifluoride?
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@sockbot 1d1
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Rolling 1d1: NaN Sum: NaN
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How on earth did you manage to get a divide-zero-by-zero in there? @accalia?
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easy, sockbot when given 1d1 as input loads this URL and tries to parse a number out of it.
well it ain't a number that loads for that URL.
I need to add sanity checking to that dice roller.
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HF is where chemistry gets serious.
Pity, because I would have a use for some, if only it weren't so dangerous.
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Pity, because I would have a use for some, if only it weren't so dangerous.
Oh, it gets much more serious than that. (FOOF manages to scare even those lunatics called professional chemists; oxygen in the +1 oxidation state?
) But HF is definitely beyond the point where I would want to be personally involved. It's the way it eats through glass and decalcifies the body that scare me.
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FOOF
Yeah, I've read that blog, and commented on it here, too.
eats through glass
That's exactly the application I would have for it.decalcifies the body
Yeah, that's definitely the scary part.
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On a related note: If your software absolutely follow a "download a 300 kB installer and then download the actual files during installation" scheme - why don't you make sure that your download servers are not powered by geriatric gerbils?
I'm looking at you SMART. Seriously, it's been 30 minutes now for what? A mere 10 MB?
I'm already rueing that I selected the additional clipart - because those run to the tune of 90 MB.
While we're at it: You can say about the Modern UI of Windows 8 what you want - but at least it's intended to be touchscreen friendly.
I'm not exactly sure who was the bright genius behind the UI of the SMARTboard software but he should take a long, hard look at the UI guidelines for touchscreens. I mean, if I crank those things up to their maximum resolution (1600 by 1200) then those Office2003-style buttons become a bit small.
Not to mention the rest of the atrocities:- You're never sure what gets grouped together (which makes it fun if you want to drag something you wrote to another place - I've had it grab every second letter only)
- You need to group stuff in order to enlarge them all in proportion and proper position.
- Stuff you need regularly (Grouping / Locking) is hidden in sub-submenus (proper Office2003-menus, that is)
And so on.
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Just one update: I started the installation at 2000h.
It's now 0030h over here. And it's still not done.
