Upgrade subject to access all content
When a thin glass rod is rubbed with a piece of silk the glass rod loses electrons and obtains a positive charge.
What possible change to this activity might allow the glass rod to gain electrons and obtain a negative charge?
Rub the glass rod with silk for a longer period of time.
Apply friction by rubbing the silk against the glass rod in the opposite direction.
Use a much larger piece of glass and a smaller piece of silk.
Rub the glass rod with rabbit fur instead of silk.