How Can I Prove the Electroscope Has a Negative Charge?

[shanktank]

hey all,
i'm new to the forum...just finished up the momentum and energy unit and now were on to static electricity...i was hopin i could get a bit of help with a couple questions i have:

3. A negatively charged rubber rod is momentarily touched to the knob of a neutral electroscope and then removed.
...i've gotten to the e) part of this question.
e) How could you prove that the electroscope has a negative charge?


4. A positively charged glass rod is held near the knob of a neutral electroscope.
d) Explain what happens to the leaves?
...well i figure the knob has a negative charge, the leaves have a positive charge...thus, the leaves should come together?
e)Explain what happens if the knob is grounded?
I have no idea with this one...
f) Explain what happens to the electroscope if the ground is removed and then the glass rod is removed?
Again no idea...

and finally
8 a) It is observed that a charged rubber rod will attract a small piece of paper. Explain how this occurs?
...I assume because the charged rubber rod is either negatively or positively charged, and the paper is the oppositely charged?
b) Eventually the rubber rod will "spit" the piece of paper away and will not attract anymore. Explain why this occurs?
...Once the electrons are done transferrin in the rubber rod then the chargin is done or something? haha not to sure...

Thanks for the help, never done anythin with this topic, and I'm doing it through correspondance and teachers seem to be impossible to get a hold of on the phone..
Shane

 

[Hootenanny]

It is not nesscary to double post. I have just replied to your original post.