Transcript The Basics of Electricity

```The Basics of Electricity
Current and Voltage
An electric current is the movement of electrons ( negative charges ).
Current is measured in units called Amps ( A ).
In a conductor ( all metals, carbon ) the electrons are free to move.
If the conductor is connected to a voltage supply ( mains, battery ) the
electrons are given the energy they need to move.
Voltage is measured in units called Volts ( V ).
Appliances
The mains and a battery supply electrical energy.
Appliances change this electrical energy to another form.
Some typical main energy changes that take place in everyday
appliances:
Aplicación
Energy Change
Kettle
electrical
heat
Lamp
electrical
light
electrical
sound
Food Mixer
electrical
kinetic
Power
The Power of an appliance tells us how quickly it uses up electrical energy.
Power is measured in units called Watts ( W ).
High Power appliances need a bigger electric current.
Fuses
Every appliance has a fuse ( usually found in its plug ).
The fuse protects the flex connecting the appliance from overheating.
If too large a current flows through the flex the fuse melts.
The gap created means no current can flow and the appliance is safe.
Appliances usually need a 3 A or a 13 A fuse.
These are the maximum currents that can flow before the fuse melts.
Appliance
Power (W)
Fuse (A)
What energy do appliances with the biggest Powers produce?
Heat Energy appliances have the biggest Powers
What size of fuse do appliances with a Power greater than 700 W need?
Power more than or equal to 700 W needs a 13 A fuse
What about appliances with a Power less than 700 W?
Power less than 700 W needs a 3 A fuse
What appliances are exceptions to this rule?
Fridge and a hoover are exceptions
Why do these appliances require a bigger fuse?
They both have an electric motor
Choosing a Fuse
Appliances with a power rating up to 700 W:
use a 3A fuse
Appliances with a power rating greater than 700 W:
use a 13 A fuse
Flexes
A flex connects an appliance to a plug.
Appliances with a bigger power require a thicker flex.
Appliance
Flex Thickness
(mm2)
500 W Food Mixer
0.5
1000 W Toaster
0.75
3000 W Kettle
1.25
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