Ch. 21 Flashcards
What is the difference between electric potential and Electric potential energy
Electric potential is created by a source charge whereas electric potential energy describes the interactions between a charge and the potential
is there always electric potential even if there is no charge to experience it?
yes, there is always an electric potential
what creates electric potential energy
when a charge is moved to a region with greater electric potential, it requires more work to move the charge, this work is transformed into potential energy that is stored in the charge
what happens when a charge is moved from a region of high to low potential?
it’s speed increases as its energy is transformed into kinetic energy
How are potential differences created?
they are created by a separation of charge
what are two sources of potential differences
batteries and capacitors
how do batteries create potential differences
they use chemical means to separate charge and produce a potential difference
how do capacitors create a separation of charge
the opposite charges on the plates of a capacitor create a potential difference between the plates
what are equipotential surfaces
at all points, the potential is the same
how are electric fields and equipotential surfaces related
electric field is always perpendicular to an equipotential surface
what happens to a charge as it moves along an equupotenital surface
the potential energy does not change as it is not moving along the field
what direction does the electric field point relative to the potential
it points downhill, in the direction of decreasing V
what are the 5 qualities of a conductor in electrostatic equilibrium
all excess charge is on the surface
the electric field on the interior is zero
the exterior electric field is perpendicular to the surface
the field strength is the largest at sharp corners
The entire conductor is at the same potential and so the surface is an equipotential
what can capacitors do in relation to charge and energy
they can be used to store charge and potential energy
how are work and potential energy connected
the amount of work done is equal to the amount of potential energy stored
how is a objects potential energy related to its charge
if a object has a greater charge, it will require greater amounts of work to move, so it will store more potential energy
if ∆KE is positive, what happens to the speed of the charge and how did it move relative to the potential
it sped up, it moved from a region of high potential to low
if ∆KE is negative, what happens to the speed of the charge and how did it move relative to the potential
it slowed down, it moved from a region of low potential energy to high
when q is negative, what happens to the kinetic energy when it moves from a region of low potential energy to high
it is attracted to the high potential region so its Kinetic energy increases
what happens to the potential energy a negative charge as it gets closer to the point charge
its potential energy decreases and kinetic energy increases
what do source charges create
they create fields and electric potentials
if you increase the charges on two electrodes on a capacitor, what happens to the potential difference?
it increases, it is proportional
what is a diaelectric and what does it do the the electric field in a parallel plate capacitor
it is an insulator that is polarized by the electric field in the capacitor.
This causes it to create its own electric field in the opposite direction and this creates a smaller net electric field
what does the presence of a dielectric do to the capacitance
it increases the capacitance
how is energy stored in a capacitor
it is stored in the volume of the electric field
the electric potential outside a charged sphere is the same as a point charge
what does the electric field and electric potential depend on in a capacitor
the charge
what do 3 things do diaelectrics do
they decrease the electric field, decrease the electric potenital, increase the capacitance
what do you need to make a capacitor
two conducting materials and an insulator in between them
what unit is an electron volt
it is a unit of energy
what does the electric field of a parallel plate capacitor depend on
the charge and area
what does the Efield in a parallel plate capacitor depend on
it depends only on the charge of the plates and the area
what quantity is the capacitance of a parallel plate independent of?
it is independent of the potenital difference (the voltage) across the plates
what is the capacitance dependent on?
the area of the plates and the distance between them. if you decrease the distance between them, the capacitance is higher
what is a capacitance
capacity of a material object or device to store electric charge.
if there is a system with a proton and an electron, can the electric potential energy of the system be zero?
no it will be negative no matter how they are arranged
