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  • electric potential energy

    Potential energy associated with the interaction of charges

    mechanical energy

    Electric potential energy is a form of

    no friction or resistance

    Mechanical energy is conserved as long as there is

    work

    Whenever a charge is moved by another charge's electric field force,____ is done

    point charges

    no PE for

    work done

    no change in PE, no

    electric potential energy

    When a charge is moved in a uniform electric field, the change in location relates to a change in

    d

    is the displacement from reference point

    uniform

    point charges are not____ because their field weakens at a distance

    increase; decrease

    The negative sign means that the PE will ____ when the charge is negative and ______ when the charge is positive

    perpendicular

    No work is done when a charge is moved _____ to an electric field, and the PEelectric remains constant

    Electric potential

    is the potential energy associated with a charge in an electric field

    Potential difference

    is the change in electric potential

    equation for potential difference

    ∆V = ∆PEelectric/q

    volt (V)

    Unit for potential difference is the

    Electron volt

    a unit of energy, energy 1 electron gains when moved through a potential difference of 1V.

    Battery

    energy storage unit that maintains a constant potential difference between two locations called terminals

    positive----negative

    Negative charges inside the battery move from the ___ terminal to the ____

    Capacitor

    device used to store electric potential energy

    energized or charged

    When the plates are charged, the capacitor is said to be

    potential difference

    The plates become charged by connecting them to a source of

    Capacitance

    is the ratio of the charge to the potential difference of the plates

    Unit = farad (F), which is one coulomb/volt

    unit for capacitance

    ε

    is the permittivity of the material,

    εo

    is the permittivity in a vacuum, which is 8.85x10-12 C2/(Nm2)

    material

    Changing the____ between the plates of a capacitor will change how much charge it can hold

    dielectric

    Capacitors made with a _____ between the plates hold more charge - this book assumes vacuum between plates

    connected to a material that conducts

    Once a capacitor is charged it will remain so until

    zero

    When discharged, the charges move between the plates until the potential difference is

    PE

    A charged capacitor stores

    transfer of energy

    Work done to move the charge is a measure of the

    Electric Current

    Movement of electric charge

    Luigi Galvani

    discovered that animals conduct electricity - frog legs twitched when conducting electrical experiments near the frog

    Current

    is the rate of charge transfer

    Unit = ampere (A or amps), one coulomb per second

    unit for current

    Positive charge movement

    Conventional current =

    charge carrier

    Current motion is actually made up of positive, negative or movement of both - called

    Drift velocity =

    net velocity of the charge carriers, very small (~25mm/s)

    Electrons

    in the conductor move along a zig-zag due to their vibrations - causes collisions and energy transfer

    slowly

    Electrons move ____ through a conductor in the opposite direction from the electric field - however E reaches the electrons at nearly c

    resistance

    Opposition of the motion of charge through a conductor

    Unit: ohm (Ω)

    unit for resistance

    constant

    Resistance is____ over a range of potential differences

    less resistance

    Greater area =

    greater resistance

    Longer material =

    higher resistance

    Higher temperature =

    Ohms law

    V = IR

    ohmic materials

    Ohm's law only applies to materials that have constant resistance - called

    Resistors

    control the amount of current in a conductor

    Saltwater and perspiration

    lower the body's resistance

    Potentiometer -

    a type of resistor that allows the user to change the potential difference across a conductor - used on volume control knobs, dimmer light switch, video game controllers

    high---low

    Free electrons in a conductor move from areas of ___ electric potential to areas of ___ electric potential

    constant

    Potential difference maintains ____ in a circuit

    Direct Current (DC) -

    electrons move in one direction, from low electric potential to high electric potential (remember conventional current is flow of positive charge) - conventional current moves from positive terminal to negative terminal

    Alternating Current (AC) -

    terminals causing potential difference are constantly changing sign, causes charges to just vibrate back and forth rather than flow

    Electric Power -

    rate of energy conversion

    Unit: Watt (W), one joule per second

    unit for electric power

    kilowatt-hours.

    Power companies measure energy usage in

    W/s, not kWh

    SI unit for electrical energy is

    I

    variable for current

    A

    variable for ampere

    R

    variable for resistance

    Ω

    variable for ohm

    V

    variable for potential difference

    V

    variable for volt

    E

    variable for electrical energy

    J

    variable for joule

    Series Circuit

    -one path

    Series Circuit

    -constant I

    Series Circuit

    -sum up V

    Parallel Circuit

    -2 or more paths

    Parallel Circuit

    -constant V

    Parallel Circuit

    -sum up I

    electromotive force

    EMF

    volts

    unit for EMF

    Series Circuit

    -Req> any R of a device

    Parallel Circuit

    -Req< any components resistance

    Series Circuit

    -Req= Ra+Rb+Rc....

    Parallel Circuit

    Req=(1/Ra +1/Rb...)^-1

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