1. Electric Current

2. Recap:- conductors and insulators
Why do metals conduct electricity and insulators do not?
Conductors have ‘free’ electrons
Insulators have NO ‘free’ electrons

3. Electric current
Electricity in wires is a flow of electrons along the wire.
What do we call this flow of electrons?
Electrical current

4. Direct current
Cells and batteries supply direct current, in which the current only flows in one direction.
Alternating current
Generators produce alternating current, in which the current constantly changes direction.

5. More accurate diagram to show flow of electrons in wire

6. Definition of electric current
Electric current is the RATE of flow of charge
What does mean?
This means the amount of charge passing a point in 1 second in a circuit is the electric current.
Remember
electrons are
negatively charged

7. Mathematical definition of electric current
Note for higher paper you are expected to be able rearrange this equation

8. Questions