exam 1 physics

Benjamin franklin demonstrated
connection between lightning and___

static electricity

Who conducted experiments to use static electricity to stimulate
contractions in the leg muscles of dead frogs?

Luigi Galvani

who experimented with various combinations of metals and developed the battery.

Alessandro Volta

what is the Greek word for amber?

elektron

Ancient Greeks observed effects of electric charge since 600 BC by _____

Rubbing amber against fur show it can attract small, lightweight objects

what are the two types of charges (q)

Positive (+q) and Negative (-q)

The force between charges _____ with distance

decreases

like charges ____

repel

unlike charges _____

attract

Charges were named by ____

Benjamin Franklin

The atom consists of a positively charged nucleus,
orbited by negatively charged _____

electrons (-)

The nucleus contains the ____

protons (+) and neutrons (no charge).

the electron is a ____ particle

fundemental

the electron is a fundamental particle which means

it cannot be broken down further

why does the vast majority of an atom’s mass resides in the
nucleus

The proton is 2000 times heavier than the electron

The total electric charge of the universe is a
constant because____

Electric charge is conserved

atom that has lost an electron is now a____

positive ion

Conductors are materials in
which the electric charges move

freely so

most conductors are _____

metal

Insulators are materials in which
electric charges

do not move
freely

Most insulators are

non-metal

ex. glass and rubber

semiconductor characteristics are

between those of insulators and conductors

conduction

charging by touching each other

induction

charging WITHOUT touch

Coulomb shows that an electrical force is inversely proportional to

the square of the separation between the two particles and is along the line joining them

Coulomb shows that an electrical force is proportional to

the product of the magnitudes of the charges q1 and q2 on the two particles

The resultant force on any one charge equals

the vector sum of the forces exerted by the other individual charges that are
present

the force is attractive if the charges are

of opposite sign

A field conceptualizes and maps

the force surrounding any object and acts on the another object at a distance
without any physical connection

An electric field is said to exist in

the region of space around a charged object.

The direction of the force depends on the

sign of the charge

The electric field of a point charge points ____ from a positive charge

away

The electric field of a point charge points ____ a negative charge

toward

electric field lines were introduced by

Michale faraday

field lines start at ____ charges or infinity

positive

field lines end at ___ charged or infinity

negative

field lines are more dense where the field is ____

stronger

the number of field lines drawn is proportional to the ____ of the charge

magnitude

no two field lines cannot ____ each other

cross

an electric dipole consists of

two equal and opposite charges

when an electric field is applied to a conductor, free charges inside the conductor move until the field is ______ to the surface

perpendicular

the electric field is zero everywhere inside a _______

conductor

the electric field just outside of a charged conductor is ______ to its surface

perpendicular

the excess charge on a conductor resides entirely on its ____

surfaces

on irregularly shaped objects, the charge accumulates at _____ and the electric is most intense at ____

sharp points, sharp points

A charge accelerated by an electric field is analogous to

a mass going down a hill

(In both cases, potential energy is converted to another form)

Work done to accelerate a positive charge from rest is _____ and results from a loss in ____

positive work, electric potential energy

the change in potential energy is the _____ of the work

negative

electric potential units

SI unit: Joule/Coulomb (J/C) = Volt (V)

Voltage is the term commonly used for

the potential difference between two points, e.g. a battery.

Electric Field (E) points in the direction of

decreasing potential with increasing distance from the source charge.

When a positive charge is placed in an electric field

- It moves in the direction of the field
– It moves from a point of higher potential to a point of lower potential
– Its electrical potential energy decreases
– Its kinetic energy increases

When a negative charge is placed in an electric field

– It moves opposite to the direction of the field
– It moves from a point of lower potential to a
point of higher potential
– Its electrical potential energy decreases
– Its kinetic energy increases

V decreases with distance, where E decreases

with distance squared

Electric potential is a scalar quantity while E is a

vector quantity

what is an equipotential surface

a surface (real or imaginary) on which all points are at the
same potential

The electric field at every point on an equipotential surface is____to the
surface

perpendicular

No work is required to move a charge at a constant speed on

an equipotential surface because the electric potential remains constant.

A capacitor is a device used to

store charge

A typical capacitor have two conducting parts not

touching

electric field is directly proportional to

the charge

• It describes how the strength of an electric field increases with more charge present. .

voltage is directly proportional to

electric field

Charge (q) is directly proportional to

voltage

the greater the voltage applied to any capacitor

the greater the charge stored in it

distance is inversely proportional to

capacitance

capacitance is

the amount of charge stored per volt

units of capacitance

si unit= farad (F)

what is a dielectric

insulating material in which the individual molecules polarize in proportion to the strength of the external electric field and therefore reduce the electric field within the material by a factor of K

The polarization of the dielectric results in a ____ electric field within it

lower

if the electric field in a dielectric becomes too large, it can ______

tear the electrons off the atoms thereby enabling the material to conduct (called dielectric breakdown )

what is the name for the electric field at which dielectric breakdown occurs

dielectric strength

capacitors in series ____ have the same potential difference across them

do not

the total potential difference (V) is the

sum of the potential difference across each one of the capacitors in series.

capacitors is a series ___ all carry the same charge

do

for capacitors in parallel, the Total capacitance (equivalent) is ____

sum of all the individual capacitors

electric force is ___ and has a ____ energy associated with it

conservative, potential

postive charges accelerate in the direction of ___

increasing potential

negative charges accelerate in the direction of

decreasing potential

equipotential surfaces are those on which the electric potential is

constant

the electric field is _____ to the equipotential surfaces

perpendicular

dielectric is an insulator that ____ a capacitors capacitance

increases

a dielectric is characterized by

its dielectric constant

a sufficiently large electric field can cause a dielectric to _____

break down

(T/F) An electrically neutral atom does not have net charge.

true

(T/F)The electric force between two charges can only be repulsive.

false; it can be attractive or repulsive depending on the charges involved.

(T/F) Field lines never start or end on charges; they form closed loops in empty space.

false; field lines originate from positive charges and terminate on negative charges.

(T/F) Field lines cross each other anywhere in space.

false ; field lines cannot cross

(T/F)Field lines are physical wires that carry charge.

false; field lines are conceptual tools used to represent electric fields and do not carry charge.

(T/F) The field lines begin on positive charges and end on negative charges.

true

Say you are charging by induction. You bring a negatively charged rod towards a neutrally charged sphere (which can be grounded). What would be the remaining net charge left on the sphere in this case? _______________________

The remaining net charge on the sphere would be positive after grounding, as electrons from the sphere would repel the negatively charged rod.

When the distance between two charges is doubled, the force between them is

reduced by a factor of 4.

(T/F) If you place a conductor inside an electric field with strength of 200 N/C, the field inside that conductor would also be 200 N/C. 

false : A conductor placed inside of an electric field will have an electric field strength of 0 N/C.

Which of the following is not a characteristic of electric charge?

Charges can freely move through insulators.

in ohms law voltage is ___ to current

directly proportional

when graphing ohms law the slope of voltage vs current is ___

the resistance

as charge moves through the battery the electrical potential energy of the system increased by

the amount of work done on the charge.

delta Q, Delta V

as charge moves through a resistor it ____ potential energy

losses

• loss through Collins with atoms in the resistor

temp of the resistor will increase as

more atoms collide

what kirchhoffs rules deals with charge conservation

junction rule

what kirchhoffs rules deals with energy conservation

loop rule