Electric charge

What are the units for charge?

coulombs (C)

What is an electrical conductor?

a material that electric charge can flow through easily

What materials are good electrical conductors & why?

- metals (e.g. copper, steel, graphite, mercury)

- because they contain delocalised electrons which means that have charged particles that are free to move

What is an electrical insulator?

a material that has a very high resistance to the flow of electric current

What materials are good electrical insulators & why?

- rubber, paper, plastic, diamond

- because these materials do not have charged particles that are free to move

What is meant by attraction & repulsion?

- opposite charges attract

- like charges repel

How are materials charged by friction?

- when insulating materials are rubbed against each other & electrons are transferred from one object to the other

- the material that gains electrons becomes negatively charged

- the material that loses electrons becomes positively charged

- the magnitude of the charge on each material is equal since they lose / gain the same number of electrons

How are materials charged by induction?

- when a charged material charges an uncharged material

- a negatively charged object will repel electrons away from the surface of a neutral object, leaving it with a slight positive charge

- a positively charged object will attract electrons towards the surface of a neutral object, leaving it with a slight negative charge

What happens when the charged object is removed when charging by induction?

the charges redistribute & the other object becomes neutral again

What is static electricity?

- when electric charges are not free to move / stationary

- this occurs best with insulators

What are some uses of static electricity?

- paint spraying

- ink-jet printers

- photocopiers

What are some dangers of static electrcity?

- can cause electric shocks

- if a spark is created it can cause a fire or explosion (e.g. when fueling aircrafts or tankers)