Electrostatics Flashcards
What are the three particles in an atom?
Protons electrons and neutrons
What is the mass of the three particles?
Proton- 1
Neutron- 1
Electron -1/2000
What is the charge of the three particles?
Proton- +1
Neutron- 0
Electron- -1
What is the location of the three particles?
Proton- in the nucleus
Neutron- in the nucleus
Electron- orbiting the nucleus
What is the atom mostly made up of?
Empty space
Give a short summary of what happened in Rutherford’s experiment
Ernest Rutherford carried out an experiment on his theory on the structure of an atom. He fired alpha particles (2 neutrons, 2 protons) at thin gold foil. Most of them passed straight through but one occasionally fired back.
What happened previously to Rutherford’s experiment?
Physicists thought of the atomical structure like a plum pudding. J.J Thompson had already shown there were small particles in the atom with a negative charge but knew that overall atoms had a neutral charge. This meant there had to be a positive charge to cancel out the negative charge.
What were the conclusions of Rutherford’s experiment?
The atom must be made of mostly empty space.
There must be a positive charge to repel the alpha particles.
Fill the blank:
We can make things charged by rubbing 2 ????? together.
Insulators
What happens when a polythene rod is rubbed with a duster then put near small pieces of tissue paper and why?
It will pick the paper up because the polythene rod becomes negatively charged when rubbed with a duster. Electrons transfer from the duster to the rod making it negatively charged. This leaves the duster with a positive charge as it has less electrons.
What happens when an acetate rod is rubbed with a duster then placed next to a running stream of water from a tap and why?
The water will be deflected by the rod. This is because the rod will become positively charged when rubbed with a duster as electrons transfer from the rod to the duster, leaving the acetate positively charged.
What happens when you charge 2 polythene rods with a duster, suspend one with string, hold the other one near and why?
The suspended rod will spin away because they are both negatively charged.
What happens when you charge a polythene rod and an acetate rod with a duster, suspend one with string, hold the other rod near and why?
The suspended rod will spin towards the other rod because the polythene rod is negatively charged whereas the acetate rod is positively charged.
Fill in the blanks:
Charged objects exert a ______ on each other.
Like charges _____.
Unlike charged _______.
Only the________charges are able to move from one object to another close by.
Force
Repel
Attract
Negative
Explain how an electrostatic paint sprayer works.
The paint is given a charge as it leaves the container. The object being painted has the opposite charge to the paint. There is little waste as the object and paint have opposite charges so they attract.
The object also has a nice, even coat because all the paint has the same charge so repels.
Explain how an electrostatic smoke precipitator works.
There is a charged grid that gives smoke particles a charge. There are metal plates above the grid with the opposite charge. Sometimes the grid and plates are turned off and the metal plates are hot with mechanical hammers. The soot is then collected.
Explain how an earthing cable works.
When an object like an aeroplane drives, it creates friction against the air. This is dangerous as if someone were to get out at that point, they would get a nasty electric shock because they would become a path for excess electrons to escape to the ground. The earthing cable provides a safe path for excess electrons to escape to the ground.
Explain how a lighting rod works.
A lightning rod is placed at the highest point on a building, aiming to attract lighting. When lightning hits it, copper and aluminium cables provide a pathway for the lightning to go to the ground without harming the building.
