P2.1 Static and Current Elelctricity Flashcards
Describe the structure of an atom.
Atoms contain positively charge protons and negatively charged neutrons. Protons are found in the nucleus with neutrons, which have no charge. The electrons are on shells surrounding the nucleus.
How do you create an electrostatic charge?
If you rub two insulating materials together electrons can be transferred from one to the other incurring an electrostatic current
Describe the laws of attraction and repulsion.
If two objects have the same charge they attract each other, if they have opposites charges they repeal each other. The object which has the charge will be attracted to the object which lost electrons.
How would an electrostatic charge build up on a person?
By walking on a carpet or sitting in a chair, humans can gain an electric charge. You feel the shock when it discharges through a metal object because the charge is carried through the object and to the ground. This is called earthing.
Why does lightning happen?
Static electricity can build up on clouds because of charged particles flowing through the atmosphere. This causes lightning.
How do you stop electrostatic charges building up on fuel tanks and aeroplanes becoming a problem?
The hose which fills the tank is made up of a conducting material so there aren’t any sparks.
A bonding line is attached to the aeroplane before it is refuelled, earthing it.
Describe the uses of static electricity.
It can be used in insecticide sprayers and electrostatic spray painting.
The object to be sprayed is given a negative charge. The metal spray nozzle is connected to the positive terminal of an electrical supply, and the droplets are given a positive charge. They repeal each other, so spread out and are attracted to the object, the spray formed is fine.
What is an electric current?
Rate of flow of a charge.
Why does a current flow in metals?
Metals have free moving electrons, allowing the current to move, unlike in insulating materials where the electrons don’t move.
What are d.c and a.c?
D.C- direct current flows in one direction and can be supplied by batteries.
A.C- current flows in alternating directions.
What is a static current?
A static current is a current which is caused by an electrostatic charge building up on an insulating material.
What is the equation for charge?
Charge=current x time
Q=Ixt
