# Energy Notes for Pre-AP Physics I Essay

Submitted By Jennifer-Pena
Words: 695
Pages: 3

Conductor:
In a conductor (usually metal) many of the electrons are free to move around within the conductor.
"sea of electrons": movement of the electrons looks like a flowing sea. a charged object will always be attracted by a conductor.
Positively charged object near conductor = attraction
Negatively charged object near conductor = electrons repel Protons are fixed in place because they make up the mass of the conductor When no charged object is near the conductor, the electrons evenly distribute themselves within the conductor.
Insulator:
In an insulator (such as plastic, rubber, glass, etc) the electrons are not free to move around the entire object.
Generally restricted to moving only around the atom they are attached to
Can move from one side of the atom to the other but are unable to leave the atom Charges stay where you put them on an insulator. A neutral insulator will always be attracted to a charged object.
Losing charge (charge theft):
Neutrally charged objects (conductors or insulators) will always be attracted to a charged object.
As the objects reach the charges object they end up picking up excess charge and now have same charge as object so they are repelled by it and once they leave, they take charges with them.
Particles in the air removes excess charge and leaves it neutrally charged
Moist days; more water particles; steal charge more rapidly. Dry days; fewer particles; get discharged once we touch(shock)
Triboelectricity:
Whenever two different materials rub against each other it is less likely that one will leave with more electrons than it started with the other will leave with less.
Electrons are stolen from you by carpet: + charge; negative charges are free to move
Electrons are stolen from carpet by you: - charge; electrons will jump from you to another place
Triboelectric series (ex: rubber rubbed w/ wool, rubber = -, wool = +)
The item that is higher on the list will end up more positive and the lower one will end up more negatively charged.
Coulomb’s Law:
Any two charged objects will create a force on each other. Opposite charges will produce an attractive force while similar charges will produce a repulsive force.
The greater the charges, the greater the force. The greater the distance between them, the smaller the force.
The forces are force pairs of each other so they will always be equal in size and opposite in direction.
Quantity of charge can be measured in either elementary charges (an elementary charge is the amount of charge on one electron or proton) or in Coulombs
Forces on multiple charges:
The forces are large when two charges are near each other but get smaller as they move…