how would you use an electroscope to determine the nature of charge of a charged body
Answers
Let the electroscope get charged with negative charge, by
touching a negatively charged ebonite rod to the metal disc of the electroscope. The leaves of the electroscope open up (diverge).Now touch the body to be tested with the metal disc of the charged electroscope.
If the divergence of the leaves increases, the body has similar charge that is the given body is also negatively charged.
If the divergence of the leaves decreases, the body has unlike charge that is the given body is positively charged.
Therefore:
1.)ground the electroscope through touching it with you fingers (removing any excess charge); one can assume it is neutral/has no net charged at this point.
2.) touch one of the charged rods to the electroscope. The leaves should rise with an unknown charge.
3.) Vigorously rub the uncharged glass rod with a paper towel to give it a positive charge.
4.) bring the positively charged rod close to the Electroscope. If the leaves are repulsed, then you know that the glass rod of unknown charge was/is of the same charge, and therefore is positively charged. Opposite charges attract. Therefore if the leaves attract one knows that the glass rod of unknown charge was negatively charged.
5.) [check] repeat steps 1-4 to verify that that last rod is of opposite charge.