What will you observe when the metal top of an electroscope is touched with:
(a) a positively charged object?
(b) a negatively charged object?
If an object made of substance A is rubbed with an object made of substance B, then A becomes positively charged and B becomes negatively charged. If, however, an object made of substance A is rubbed against an object made of substance C, then A become negatively charged. What will happen if an object made of substance B is rubbed against an object made of substance C?