Science Day Report

As I foreshadowed here late last week, I announced to the household on Friday night that I had declared that Saturday would be Science Day, and tried (with very limited success) to muster excitement about making a cloud chamber, crushing cans with air pressure, and (possibly) a secret evening fire act.  

So, how did it go?  Not too bad, really.  I can report as follows:

1.  Building a  mini cloud chamber:   I tried two containers, one an old round (and small) gold fish bowl, and the other a plastic container.  The design problem was how to seal the bottom.  I used plasticine like on one of the Youtube videos I had watched, but it doesn't seal so well when it is attached to a dry ice cooled metal plate.   It seemed that I could only get the right supersaturated (with isopropanol) layer to be just above the plate (perhaps less than a centimetre high) so that did limit the amount and length of trails you could see.  But yes! - we did watch vapour trails and I tried to explain about muons and cosmic rays and fusion in stars and stuff like that, to some glazed face reactions. I think I am going to have to make my own slideshow presentation about this and force them to watch it.  ("There will be a test afterwards", I like to keep threatening my kids after I try to explain something.  I actually did administer a written test once after the visit to the Macarthur Museum in Brisbane.)

I'm also happy to confirm that isopropanol is sold at Bunnings and costs about $8.  A kilo of dry ice was $10, and the plasticene $2.50. I think it is very cool that for $20 I was able to demonstrate at home  the invisible rain of muons and other particles.  The only trick is convincing children how impressive that is - a task that is beyond mere science!

I took a video of the second container, which did not work very well compared to the first, but you can see one little vapour trail.  Will post it tomorrow.

Update:



 2.  Crushing a beer can with air pressure.  There are many Youtube videos showing this,and it does work as advertised and makes a somewhat surprising crunch.  Everyone should try it.   We also did an olive oil can, but the seal wasn't perfect and while it did crush, it was less satisfying.

3.   Fun with CO2.  We had lots of dry ice left, and so did the usual bubbling water, but also put out flames by pouring it over the candle, etc.  But the trick that most impressed the household was floating soap bubbles on it. It does look odd:



4.  Firebreathing with cornflower.  Works well, and that was just using a couple of bar b que matches to light it.   I secretly showed one child, then the other, and then decided I would risk matrimonial disapproval and showed all three together.  She was OK with it, thankfully.

Here's the video, edited to remove me:

 

So, success all round, pretty much.  I'm available for parties for nerdy kids, you know.