Topic 1a/2a Flashcards
Electrons?
Negative electrons. They give the atom it’s overall size. Virtually no mass.
Proton mass and charge?
Mass 1
Charge +1
Neutron mass and charge?
Mass 1
Charge 0
Electron mass and charge?
Mass 1/2000
Charge -1
How is static built up and how does it work?
The build up of static is caused by friction. When two insulating materials are rubbed together, electrons scrape off and are dumped on one another. This leaves a positive static charge one one and a negative static charge on the other. Only the electrons can move not the protons so the way they go depends on the two materials.
Example of static caused by friction? (Polythene rod)
Polythene and acetate rods being rubbed with a cloth duster. With the polythene rod the electrons move from the duster to the rod. The rod becomes negatively charged because of the electron movement and the duster is left with an equal positive charge.
Example of static caused by friction? (Acetate rod)
With the acetate rod, electrons move from the rod to the duster. The duster becomes negatively charged because of the electron movement and the duster is left with an equal positive charge.
What can static electricity cause?
Clothing crackles
Car shocks
Shocks from door handles
Clothing crackles?
When synthetic clothes are dragged over each other, electrons get scrapped off. This leaves static charges on both parts. This leads to attraction and little sparks as the charges rearrange themselves.
Car shocks?
Static charge builds up between clothes and synthetic car seats. The friction between the two causes electrons to be scrapped off. When you get out of the car and touch the metal door, the charge flows and can give you a shock. A conducting strip hand down behind some cars to allow a safe discharge to the earth.
Shocks from door handles?
If you walk on nylon carpet wearing insulating soles, there will be a transfer of electrons from the carpet to you and the charge builds up on your body. If you then touch a metal door handle, the charge flows and gives you a shock.
Nucleus?
Makes up most of the mass. Contains positive protons and neutral neutrons. This gives an overall positive charge.
Rubbing a balloon?
Electrons transfer from hair to the balloon, giving it a negative charge. It then sticks to a wall because the negative charges on the balloon repel the negative charges on the wall to just leave the positive ones. Then they attract and stick.
Paint sprayers?
Bikes and cars are painted by electrostatic paint sprayers. The spray gun is charged which charges up the paint. Each paint drop repels each other to give a fine spray. The object getting sprayed is given an opposite charge to attract the paint. This gives an even coat and hardly any paint is wasted.
Fuelling with electrostatic charges?
As the fuel flows out the filter pipe into an aircraft, static can build up. This can lead to a spark that can cause an explosion in dusty of fumey places like a petrol station. This is solved by earthing an object.
