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Dangers and uses of static electricity (Dangers (Petrol stations (the…
Dangers and uses of static electricity
Where it happens
When you walk across some types of carpet, you may end up with an unbalanced electric charge.
if you then touch a conductor, such as a metal tap, electrons will flow between the tap and you.
Sometimes there is a spark and you may feel a small electric shock.
The electrons flow in whichever direction removes the excess charge and you become
discharged or earthed
Dangers
static electricity builds up in the clouds due to friction between particles of ice and water, which are moved by air currents.
When the charge is large enough, charged particles travel through the air between the cloud and the earth.
Causing lightening (
and thunder
)
Lightening can be dangerous and so to discharge it safely, big buildings have big lightening conductors connected to the earth so the building is earthed.
Sparks can be dangerous
example
when there is fuel vapour that could ignite.
this can be a problem for refuelling aircraft, which often become charged when flying through the air.
a charge can also build up when fuel flows through a pipe.
To prevent a spark between a fuel pipe and an aircraft, a 'bonding line' is connected to the earth the aircraft before refuelling begins.
Petrol stations
the storage pipes and hoses are earthed.
cars are earthed through their wheels, which contain a form of carbon that makes them conductors
People are earthed when they touch the metal of the car or the pump
Uses of static electricity
Electrostatic
spraying makes use of static electricity
Example
when spraying crops with insecticide, electrodes on the spray nozzle charge the spray droplets as they pass.
The charged droplets spread out because they repel each other and then they are attracted to the plants by induction.
This means that the spray spreads around the plant even underneath it.
Less falls on the ground and farmers dont have to use as much.