48 terms

Honors Physics Chapter 16

STUDY
PLAY
positive and negative
Two types of charges:
repel
Like charges
attract
Opposite charges
dry
One noticed static charges more on _____ days because there is not moisture in the air to "connect" the charges
electrons
move between material rather than protons
Ions
atoms that have gain or lost electrons and therefore have a charge
neutral
1 proton balances 1 electron and the net charge is zero
transferred
Charges cannot be created or destroyed, they can only be
quantized
Millikan discovered that a charged object's charge is always a multiple of a fundamental charge, e - called...
e
is the charge of one electron (-1.60 x 10-19 Coulombs)
Coulomb (C)
SI unit for charge is the
Electrical Conductors
materials that allow charges to flow easily from them (most metals)
Electrical Insulators
materials that do not allow charge to flow through them (glass, plastic, rubber, silk)
Semiconductors
normally insulators, but adding specific atoms as impurities can turn them into conductors (silicon, germanium - used a lot in electronics)
Superconductors
zero electrical resistance when below a certain temperature - can conduct electricity without heating up
Charging by Contact
rubbing two materials together - one object rubs the electrons off the other, making it positively charged
contact
Both insulators and conductors can be charged by
Grounded
conductor connected to the Earth by a conducting wire or copper pipe
Charging by Induction
A neutral conductor is brought near another charged object, then the conductor is grounded - no touching necessary
conductors
Only ____ can become charged by induction
Polarization
shifting of charge within an atom
shifting of charge
The _____ within an insulator can make its surface act like a charged object
zero
Polarized objects still have a net charge of
greater
The closer two charges are, the____ the force of attraction or repulsion between them
Coulomb's Law
F = (kq1q2)/r2
(k = 8.9875 x 109 Nm2/C2)
is called Coulomb's Constant
resultant force
Like any other force, the vector sum of all charge forces acting on an object is called the
Principle of Superposition
If charges are not linear, you must find the x- and y- components and then add the x-components and y-components and use the Pythagorean Theorem to find the resultant force - Called the
Field Force
force between two objects that are not in contact with each other
attractive or repulsive
Electric forces can be either
gravitational force
Electric force is much stronger than
Electric field
area around a charge where the charge can be "felt" by another object
test charge (+)
is used to detect the presence of an electric field
qo
is the small, positive test charge
N/C
Electric Field units are
Direction of field
is the direction of the force on the positive test charge
vector (direction)
E is a
outward
When the Field is positively charged, the direction is
inward
When the Field is negatively charged, the direction is
stronger charge
Lines closer together =
q
variable for charge
positive charge to negative charge
Lines drawn from
Electric Dipole
two equal in strength, but opposite charges - field lines are identical and turn away from each other
conductor - electrostatic equilibrium
No net motion of the charges in a
zero
Electric field is____ inside the conductor
the outside of the material
Charges reside only on
material's surface
Electric field is perpendicular to the
irregularly shaped objects
Charges accumulate at points for