Do like charges repel or attract each other?
Like charges repel each other; opposite charges attract.
If you rub a polythene rod with a dry cloth, will it become positively charged, negatively charged, or neutral, and why?
The polythene rod becomes negatively charged due to it gaining electrons from the dry cloth, which consequently becomes positively charged.
A perspex rod becomes positively charged when rubbed with a dry cloth. Does this mean it has gained or lost electrons, and what charge would the dry cloth have?
The perspex rod would have lost electrons if it had become positively charged as the electrons are negatively charged. The dry cloth would have recieved these electrons and therefore become negatively charged.
What is the electric current?
The rate of the flow of electrons.
Why do metals conduct electricity and why do insulators not?
Metals conduct eletricity because of the delocalised electrons which when connected to a power source, get attracted to the positive source, forcing them to move around the circuit. Insulating materials don't conduct electricity because their electrons are all held in atoms.
When can a conductor not hold charge?
A conductor can not hold charge if it is in contact with the ground, because the electrons transfer between the conductor and the ground.
How do we discharge a conductor safely?
By earthing it - connecting it to the ground - allows electrons to pass between conductor and the ground.
What happens to an object if it gains too much charge?
The object will produce sparks.
What can we do to eliminate static electricity?
We can :
- Use antistatic materials - used in operating theatres
- Earth metal pipes and other metal objects - in use of flammable fuels