electrostatics

Progress is slow

Have been playing with electrostatics quite a bit lately, partly to try and establish how to guarantee that the demos will work as expected (see previous blog).
When it works well it is actually very impressive, but taking a video of this gives the impression that it is always this straightforward, which is not at all helpful to new teachers who will expect everything to work perfectly first time, and may be silly enough to not have gone through it themselves beforehand.

On the I.T. front, I stuck a few aul’ videos onto youtube and googlevideo. They certainly allow for better quality viewing than downloading straight from thephysicsteacher site, and also allow for feedback which will hopefully prove useful.
The disadvantage is that they are almost definitely blocked in most schools, so can only be viewed at home.
Youtube has a time limit of 10 minutes, which is a pity because apart from short demonstrations, many of the video clips I have are twice as long. Googlevideo is not as popular and I have also had quite a few problems uploading. This sure is one big pain in the rear end.

Bloody Electrostatics demonstrations

Got up at 6:30 this morning to be in school at 7:15 to have lots of time to prepare for a form 5 class on electrostatics which I wanted to film.
Now I’m not normally this dedicated, but because it was being videod (‘videoed’?) I wanted to get everything right.
Electrostatics is dodgy at the best of times, but at half eight this morning every thing was going like a dream. To such an extent that I started wondering why other teachers made such a big deal of it. Maybe they should prepare more – like I was doing.

Class began at about 12 o clock. I started the video, and spent the first ten minutes correcting homework on the board, then started into the demos.
Not one worked as well as it did in the morning.
Some didn’t work at all.
It was baffling, frustrating and funny in roughly equal measures.

I take that back.
Mostly it was frustrating, especially since I had prepared it so well.
The smug factor had felt good too.

It’s possible that atmospheric conditions had changed over a few hours, but I suspect one other variable was that the classroom had had four sets of students sit in there for forty minutes at a time, each breathing in nice clean dry air, and breathing out air which contained a higher percentage of water. As one of the students said: “Come on now sir, I know you blame us for everything else, but you can’t seriously think you can blame us for this one.”
So;
tomorrow I repeat the process first thing in the morning, then again a few hours later, and if the same thing happens I think I might use hot plates or bunsen burners to dry out the air for a spell and then repeat (what happens the water / water vapour when the air drys? Where does it go?).
Edge of the seat stuff this . . .