# Three pithballs are suspended from thin threads

1. Feb 16, 2010

### wrthwrld

a) Three pithballs are suspended from thin threads.Various objects are then rubbed against other
objects (nylon against silk, glass against polyester, etc.) and each of the pithballs is charged by
touching them with one of these objects. It is found that pithballs 1 and 2 attract each other and
that pithballs 2 and 3 repel each other. From this we can conclude that:
1. 1 and 3 carry charges of opposite sign .
2. 1 and 3 carry charges of equal sign .
3. All three carry the charges of the same sign .
4. One of the objects carries no charge .
5. We need to do more experiments to determine the sign of the charges .

^so i know opposite charges attract and negative charges repel

i chose 1 and 5 to be correct choices because I imagine the sequence of charges to be:
+ - - or - + +

is there a possible way to determine the sign of the charges?
I'd like to be reassured or told what is wrong with my reasoning

2. Feb 16, 2010

### rl.bhat

Even an uncharged body is attracted by a charged body.