How would you use a pith ball to prove an object was charged? How would you use a pith ball to prove that an object was charged negatively?

How would you use a pith ball to prove that an object was charged positively?

Acm ruler with main graduations from 1 to 10 from left to right there are 10 secondary graduations between each of the main graduations there is a line that begins. at the left end of the ruler 10 secondary graduations to the left of the “1 main graduation the right end of the line ends on the eighth secondary graduation to the right of 3 how long is the line