Australia's Science Forum

hello,
Have had a request from a teacher to check the electroscopes to see if they are working before he uses them in a prac?
Please Tell me how to check this, I have nooooo idea.

Many thanks Trish.

My guess would be just to 'try them out' like you would use them in a prac i.e. charge some ebonite and perspex rods (with wool and silk) and wave them near the top, to see if the needle moves?

That's what I'd do, anyway. Not sure if it's right!

Get out your ebonite and perspex rods and your wool and silk. Rub the rods to charge them and hold them close to the top of the electroscope. The needle should swing either positive or negative. Be careful not to touch the charged end of the rod with anything (including the electroscope) as this will de-charge (uncharge?) it.

I'm with you Megz, that's what I'd do too. Could the weather affect them?
Lou P.

"An electroscope is a charge-detecting device which depicts the presence of a charge on the apparatus itself or upon other objects in the nearby vicinity. The presence of a charge on an electroscope is depicted by the deflection of its needle from its usual upright position. The needle, being free to rotate about its pivot, will be deflected whenever the charge in the needle is the same as the charge in the upright support upon which it balances. Since the electroscope plate, support, and needle are connected and made of a conducting material, any charge upon the electroscope will be uniformly distributed about the entire conductor. Thus, if an electroscope acquires an overall positive charge, this positive charge will be spread about the entire electroscope - plate, support and needle. Since like charges repel, the positively-charged support and the positively-charged needle will repel each other, causing a deflection of the needle."

Rosalie I think the word you were looking for is discharge MariaC

A faster way than rubbing perspex/ebony rods is Prof Bunsen's Fun-Fly Stick! (its a hand-held mini Van der Graaf) Just turn it on (without the fun-flyers) and move it near the electroscope/s.

Quote could the weather effect them
Yes! on rainy days and days of high humidty the teachers can have trouble getting them to work, then it's the labbies fault, after all we are gods and can control the weather!!!!!!

Xenon - I'm with you bro. The Fun Fly stick is so-o-o-o cool!

we recently bought some fun fly sticks, so much better for the kids to use than the van de graaff, which often doesnt work too well in wet weather. The fun fly toys that come supplied dont last very long but the kids can make their own with tissue paper and also they make a "tina turner hair piece" - a circle of tissue paper with cuts towards the centre, place it on top of the fun fly stick and the "hair" stands up on end. Then move your hand slowly towards the hair and it will jump to your hand. Making their own fun fly toys also makes the lesson a bit longer and the kids can experiment with shapes and size etc.
Lots of fun!
Jen

Thanks for your replys,
Was able to give them ago, found 3 not working and will try to fix them when time permits.
But thanks again, very true on the saying you learn something new everyday, esp in this job.
Trish

Hi
Can you tell me what a fun fly stick is and where you get them from? Are they expensive?
Thanks
Tina

Google Prof bunsen and you will find them on their website. They look like heaps of fun

Thanks Rosalie, I'll do that.

How did your elephant's toothpaste go? Larissa is really enjoying this unit and all the pracs that you are organising for them!
Cheers
Tina

The elephants toothpaste went REALLY well!! Even I was having a heap of fun and wanted to keep going! It worked so much better than my mentos and diet coke one (which only didn't work because my contraption failed me on the day...). I hadn't tried the hot H2O2 before the day, and I just had a small amount sitting in hot water while I did the first one or two and when I got to the hot one, it really went off!!! I nearly didn't get out of the way in time. I am hoping that other teachers will see that science can be incorporated into their units and ask me to do more with their classes and help get kids excited about science at an early age.

Thats great Rosalie
just wanting to check - the hot one that worked really well - was that the 6% H2O2 or the 30%?
Cheers
Tina

(ps - my kids want to know how I can know what is going on in their class before they do! Heee heee. I tell them it is because I am a mother - I know all!!!!!! (and I have an insider on the job!). You have to keep them guessing!)
Good on you Rosalie
Tina

Hi Tina,
It was 35% that I did hot. What I did for the demo was a cold 35%, a hot 35% and a cold 6% to show slowly what was going on and talk about the reaction, and then another hot one to finish off. Hot 6% doesn't work as well as cold 35%. I'll try to post some photos later. They are still on my phone. I have one that one of the teachers took which I can put here now though
Rosalie

Wow, Rosalie - that's brilliant!

Bet the kids thought it was too - well done!