18.1 Static Electricity and Charge: Conservation of Charge

Borneo amber was mined in Sabah, Malaysia.

A piece of amber gains more electrons when rubbed with a piece of silk.
The silk has lost electrons and becomes positively charged at the same time.
The existence of static electricity has been known for a long time.
The first record of its effects was written by ancient Greeks.

A lot of the characteristics of static electricity can be explored by rubbing things together.

The spark you get from walking across a carpet is created byubbing.
The attraction of straw to recently polished amber is caused by rubbing.
Air movements under certain weather conditions result in lightning.
You can make a balloon cling to a wall by rubbing a balloon on your hair.
In dry climates, we have to be cautious of static electricity.
Before grabbing the gas nozzle, we are warned to discharge ourselves on a metal surface after sliding across the seat.
The attendants in the operating rooms have to wear a strip of aluminum foil on their bottoms to avoid creating sparks which may ignite anesthesia gases and the oxygen being used.

The effects of static electricity are explained by a physical quantity not previously introduced, called electric charge.

Positive and negative are the two types of charge.

Like charges repel, unlike charges attract.

The force between charges decreases with distance.

When various materials are rubbed together in controlled ways, there is always one type of charge on one material and another type on the other.

When glass is rubbed with silk, it becomes positively charged and negatively charged.
Since the glass and silk have different charges, they attract one another like clothes that have rubbed together in a dryer.
Two glass rods rubbed with silk will repel each other.
Two silk cloths rubbed will repel, since both have a negative charge.

A glass rod becomes positively charged when rubbed with silk.

Benjamin Franklin and other early researchers had these questions, and they interest us today.

Franklin wrote in his books and letters that he could see the effects of electric charge, but he didn't understand what caused it.

Normal matter is made of atoms, and that they contain positive and negative charges in equal amounts.

The electrons and protons are the building blocks of most matter.

Cosmic rays and nuclear decay are where charge-carrying particles are observed.
The electron and protons are rare and only survive a short time.

The planetary model of the atom is a simplified view of an atom.

The planets and the positive nucleus are much heavier than the sun.
The forces in the atom are not the same as those in the planetary system.

The charges of electrons and protons are not the same.

All charges are made of combinations of a basic unit of charge and all charged objects are integral multiples of this basic quantity of charge.
The charges are usually formed by a combination of electrons and protons.

The symbol is used for charge and the subscript shows the charge of a single electron.

The coulomb is the SI unit of charge.

The electrons have a combined charge of -1.00 coulomb.

The smallest bit of charge is the same as the smallest part of an atom.
The smallest directly observed charge is Things Great and Small: The Submicroscopic Origin of Charge.

All charge in nature is carried by electrons and protons.

We have named the charge negative.
We call them positive because they carry an equal-magnitude charge.

All other charges are also considered to be fundamental building blocks since they are carried by electrons and protons.

Two of the three fundamental building blocks of ordinary matter are electron and protons.
The third has no charge.

The figure shows a person touching a generator.

Both types of charges are present in the expanded view of a hair.
The strands of hair repel each other and stand up because of the repulsion of positive like charges.
The artist's conception of an electron and a protons in a strand of hair is shown in the blowup.

An excess of positive charge is caused when a person touches a Van de Graaff generator, causing her hair to stand on end.

There are charges in one hair.
An artist's conception of an electron and a protons show the negative and positive charges.
We can't see these particles with visible light because they are so small, but we know a lot about their properties, such as the charges they carry.

When the substructure of protons is explored by scattering extremely energetic electrons from them, it appears that there are point-like particles inside the protons.

There are still attempts to learn of the properties of quarks, which are perhaps the ultimate substructure of matter.

By rubbing materials together, charges in atoms and molecule can be separated.

Some atoms and Molecules have a greater affinity for electrons than others and will become negatively charged by close contact in rubbing, leaving the other material positively charged.
Positive charge can be caused by rubbing.
There are methods other than rubbing that can separate charges.
Batteries use combinations of substances to separate charges.
Chemical interactions can cause one battery terminal to be negative and the other to be positive.

If one material has a higher affinity for electrons than the other, charges can be separated.

Only a few of the charges are shown here.

When charges are separated, no charge is created or destroyed.

Existing charges are moved around.
The total amount of charge is always constant.

The total charge is always the same.

Mass can be created from energy in the amount.

When an electron is created, the created mass is charged.

When a charged particle is created, another with an opposite charge is created, so that the total charge is zero.
The two particles are usually related.
An electron and an antielectron would be created at the same time.

Particles have opposite signs.

When matter and antimatter are brought together, they destroy one another.
The mass of the two particles is converted to energy E, obeying the relationship.
Since the two particles have the same charge, the total charge is zero before and after the event.

There are a limited number of physical quantities.

A charge is one of energy, momentum, and angular momentum.
The physical quantities are used to explain more phenomena and form more connections than less basic quantities.
We find that conserved quantities give us insight into the rules followed by nature and hints to the organization of nature.
The weak nuclear force and the quark substructure of protons and other particles have been discovered.

The matter was created with an electron-antielectron pair.

There is no charge before or after this event.

The law of charge has never been observed to be violated.

A short list of other quantities in nature that are always conserved include Charge.
The quantities include energy, momentum, and angular momentum.

Rub a balloon on a sweater, then let go of the balloon, and it flies over and sticks to the sweater.