1. Static electricity is caused by the transfer of electrons between two objects during friction, such as hair becoming charged after rubbing against a sweater.
2. When a duster is rubbed against polythene, electrons transfer from the duster to the polythene, leaving the duster positively charged and the polythene negatively charged.
3. Insulators like silk and polythene remain charged after friction because electrons cannot move within them, while conductors like copper allow electrons to move freely and are charged through induction.