Define an electric current.
Electric current is the rate of movement of change.
State the symbol for electric current and the unit.
Symbol: I
Unit: Ampere
State the 3 main effects of electric current.
-Magnetic effect
-Heating effect
-Chemical effect
List examples of the magnetic effect.
-Bells
-Relays
-Motors
-Generators
-Transformers
-Telephones
List examples of the heating effect
-Cookers
-Water heaters
-Electric fires
-Irons
-Furnaces
-Kettles
-Soldering irons
List examples of the chemical effect
-Primary and secondary cells
-Electroplating
Describe direct current
Direct current is one that flows in one direction only around a circuit
Describe alternating current
Alternating current is one that constantly changes direction in a circuit, rising to a maximum in one direction before falling to zero and then rising to a maximum in the opposite direction.
Define a conductor
A material having a low resistance that allows electric current to flow through it.
List examples of conductors.
-Copper
-Aluminium
-Brass
-Platinum
-Silver
-Gold
-Carbon
Define an insulator.
A material having a high resistance that does not allow electric current to flow through it.
List examples of insulators.
-Plastic
-Rubber
-Glass
-Porcelain
-Air
-Paper
-Cork
-Mica
-Ceramics
-Certain oils
Define a semiconductor
A material with an electrical conductivity between that of a conductor and an insulator, it is neither a good insulator nor a good conductor under ordinary conditions, but can be made to exhibit some of the properties of each.
List examples of semiconductors
-Silicon
-Germanium
