Topic 11 Flashcards
What can happen when insulating materials are rubbed together?
They can become (statically) electrically charged
Why can insulators become electrically charged when rubbed together?
Electrons transfer from one material onto the other.
The material gaining electrons becomes negatively charged.
The material losing electrons becomes equally positively charged
What would happen when two electrically charged objects are brought close together?
They exert a force on each other
What happens when two identically charged objects are brought close together?
They exert a repulsive force on each other and repel
Why do we feel an electric shock?
When an object builds up an electrostatic charge, it needs to be “earthed” via a conductor
Electrons flow to/from the earth to balance the charge
This can also occur if you touch a charged object whilst you are earthed
Therefore causing an electric shock.
Why does lightning occur?
Clouds can build up an electrostatic charge
When this charge becomes large enough, the clouds discharge via the air to earth
AKA Lightning
Why does a charged balloon stick to the wall?
When a negatively charged ballon is placed next to a wall the negative charges in the ballon repel negative charges in the wall (electrons). This leaves the positive (induced) charge left behind which it is attracted to and it sticks.
How does Earthing (in plugs) remove excess charge?
It provides a path with a low resistance for the electrons to flow either from the device or towards the device to reduce the charge build up
How does static electricity cause danger when fuelling cars?
Static charge can build up due to the friction betwen the pipes and the fuel
When the charge builds up, a spark may be discharged.
The spark could start a fire if it reacts with the flammable fuel
This is resolved by earthing the vehicle and pump.
What is an electric field?
A region where an electric charge will experience a non-contact force.
What direction do the field lines in an electric field point?
In the direction that a positive charge would move (experience a force).
Which field is the stronger field?
How can you use electric fields to explain static electricity
The object that is statically charged will generate an electric field
This field attracts the electrons on other objects causing a flow of charge resulting in sparks
how does electrostatic spray (insecticide) work
