This question is about electrostatic charges, charging by friction, and forces between charged objects.
When rubbed with silk cloth, a cellulose acetate rod becomes positively charged. When rubbed with woollen cloth, a polythene rod becomes negatively charged. A gold-leaf electroscope is available to verify the presence and sign of electrostatic charges.
Explain how you would use this apparatus to demonstrate:
- That like charges repel each other.
- That unlike charges attract each other.
- How a gold-leaf electroscope, initially charged with a known positive charge, can be used to confirm that the rubbed polythene rod has a negative charge.