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investiagted electricity and made serval discoveries
ben frank
proposed thatelectricity is composed of two charges
ben frank
proved lightening as a form of electricity
ben frank
two ways a neutral object reacts near a charged object
charged object will repel the like charge in the neutral object and attract all of opp charge
object will polarize with opp charge at surface
polarization of a neutral object depends on
how its charges move
if the charges cannot move it is known as
insulator
non metallic
cannot conduct heat or electricity
insulator
an object whose charges move easily
conducts heat and elect
conductors
charge
quantity that can be measured
most change in electrical charge are caused by
the movement of electrons
protons are located
at the center of an atom
electrons are located
near the surface of an atom
why does electricity involve the movement of electrons
because electrons are lighter to move than protons
sound that force is proportional to the amount of charge on each of the objects
coloumb
the direction of force is only the line connecting
the charge and is attractive when opp charge and repel when same charge
van de graff generator work
machine that places a large electric charge on a sphere
like charges move away
attracted to opp charge on ball and can discharge through air creating a spark
these two are inverseley proportional square forces
gravitational
electric forces
3 differences between gravitational and electric force
grvity depends on mass electric on charge
gravity attracts electricity repels
for fundamental particles electric force is stronger
electric charge creates
forces
a charge experiences forces from
several other charges
superposition principle
electric force is the vector sum of all the forces
a good way to create a uniform electric field is with
two flat plates of opposite charge called a parallel plate capacitor
because of the E field in a capacitor a charge inside it will
move and a moving charge will be detected
3 ways electric field is considered real
imports a force on a charge
can be measured at any pount in space
everything about forces can be used to understand E fields
why is the electric fiel within a conductor zero
because if there wasnt there would be a force on those charges, however, since its in a conductor charges are free to move in response to those forces
why does a conductor have apointy part
more charges will accumulate there to be far from the other charges so the stronger E field will occur there
how lightening is produced 4
Fast moving couds sweeping charges upward
clouds become negatuvely charged while the ground is positive
air is an insulator
E builds up, the air ionizes and becomes a conductor
typical lightneing bolt transfers ___C of charge
30
the gravity field is also known as
a force field
if we move an object against the gravity field
if we move a charge in an E field
the object acquired a greater potential energy
we change its potential E
the change in energy depends on what three things
the strength of the field
the strength of the charge
distance model
Electrical potential is the
potential energy per charge
Electric potential
how much PE a positive charge of 1C would have at that point
Electric potential energy
is simply the energy or work it takes to move a known charge between two locations
electron volts
an electron in an electrical field will feed a force and accelerate. It will then pick up speed and therefore increase in KE
In an electric field, positive charges move
in the direction of electric field
In the electrical field, negative changes move
in the direction of opposite electric field
In electrical potential, positive charges accelerate in the direction of
decreasing electric potential
in electrical potential, negative charges accelerate in the direction of
increasing electric potential
In electrical potential, when it both has negative and positive charges the charge moves
to the region of lower potential E
While force and electric field depend inversely on distance squared...
PE depends inversely distance
net worth
the sum off all your positives and negatives
Net Force
the vector sum of all forces acting at one point
force components
simply projections of vectors F12 & F13 onto the x and y axis
4 importances of electric field lines
points along the E field vector at every point
start at +/- charge to infinity
more dense where field is stronger
tells which way test particles would move
superposition principle differences between Electric field vector and electrical potential
EFV at a given location is the vector sum of all electric fields at that point
EP at a given location is the scalar sum of the EP at that point due to all nearby charges
equipotential lines
lines that connect points of = electric potential
capacitor
two conductng plates with area A seperated by a distance
an electric potential diff is established between the plates using a battery. The batter causes charges to build up on each of the plates
the exact amount of charge depends o n
how much charge can be carried in a capacitor
capacitance
define the amount of charge that builds up on a capacitor for a given potential
parallel capacitor plate
two parallel plates seperated by a distance
what does and doesnt capacitance depend on
does:
ratio of quantities of charge and voltage
doesn't:
amount of charge on plates
potential diff between plates
a flow of electric charge from one place to another
electric current
when charge flows through a closed path and returns to starting point and occurs again
electric circuit
electrons in a metal wire can only move freely if
the wire is connected to a source of electrical energy
what does a battery do
uses chemical rxn to produce diff in electric potential between the two ends
ends of battery
terminals
high electric potential in a battery
low electric potential in battery
+
-
no closed path through which the electrons can flow
open circuit
electromotive force occurance
battery disconnected from a circuit and carries no current
the diff in electric potential between its terminals is referred to as
emf
the greater the current flowing through a battery the greater
the reduction in potential diff between its terminals
emf determines
the amnt of work a battery does to move a certain amount of charge around a circuit
the direction of the current in an electric circuit is the direction which
a positive test charge would move
the amount of voltage diff is called
battery's emf
EMF is not force
Weird E is not electric field and not energy
flow of positive charge
current
current 3 importanrt details
have high PE when near + poles
they are repelled by the battery's + pole
move circuit to the negative pole
how do insulators react to the flow of electrons compared to conductors
insulators resist the flow more than conductors
used to determine the resistance the flow of a current when a voltage diff is placed on it
resistance
resisting the flow of electricity
resistance
3 parts of a simple circuit and function
battery-provides charges with PE
wire-made of a conductor
load-component that does something
a high current flows from the positive to the - terminals of the battery
short circuit
switch that prevents short circuit
circuit breaker
anything that consumes or produces energy over time by a power associated with it
power
Author
kaitiek09
ID
201369
Card Set
physics
Description
physics sfsu
Updated
2/20/2013, 9:44:39 AM
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