electrostatics

protons

positively charged particles

electrons

negatively charged particles

neutrons

uncharged particles

like charges _____ while unlike charges ____

repel; attract

electric charge is _____

conserved

what does it mean for electric charge to be quantized?

when an object is charged, its charge is always a multiple of a fundamental unit of charge

charge is measured in

coulomb C

how many coulumbs create one electron

e=1.602176 × 10^-19 C

how many electrons create one coulomb of charge

C = 6.25 × 10¹⁸ e

who determined charge of single electron

robert millikan

what was the experiment that determined charge of single electron

oil drop experiment

electrical conductor

material in which charges can move freely

electrical insulator

material in which charges cannot move freely

examples of electrical conductors

gold, iron, steel, silver, copper, sea water

examples of electrical insulators

rubber, wood, glass, fabrics, plastic, air

semiconductor

material, like silicon, with electrical conductivity between a conductor and an insulator, whose ability to conduct current can be controlled

why pure silicon for semiconductor

crystalline structure with no free electrons to conduct electricity

N-type semiconductors

have extra electrons (negative charge carriers)

P-type semiconductors

have holes or missing electrons = positive charge carriers

insulators and conductors can be charged by

conduction - direct contact

conductors can be charged by

induction, the process of bringing it near another charged object and grounding the conductor (it is connected to earth)

a surface charge can be induced on insulators by polarization

with polarization, the charges within individual molecules are realigned such that the molecule has a slight charge separation

inverse squared law

intensity is inversely proportional to the square of the distance

IQ law applies to…

light, sound, grav force, electrostatic force, physical media

coulombs law

force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them

coulomb force is a

field force that is exerted by one object on another even if there is no physical contact between them

Q is considered a ____ while q is considered a ____

point charge; test charge

number of electric field lines is proportional to the

electric field strength

electric field is ____ everywhere inside the conductor

zero

any excess charge on an isolated conductor resides entirely on the conductor’s _____

outer surface

electric field just outside a charged conductor is _____ to the conductor’s surface

perpendicular

on an irregularly shaped conductor, charge tends to accumulate where the __________

radius on the surface is smallest (sharp points)

capacitor

device used to store electrical potential energy

capacitance

ability of a conductor to store energy in the form of electrically separated charges

units for capacitance is

farad, F, which equals a coulomb per volt

capacitance is

the ratio of charge to potential difference

magnitude of charge on each plate/potential difference

capacitance depends on the

size and shape of a capacitor

what can change a capacitor’s capacitance

the material between its plates

what is the effect of a dielectric

it is an insulator for reducing the strength of the electric field

examples of capacitor in medicine

pacemaker: help your heart maintain a normal rhythm and sends low energy pulses to the heart

defibrillator: prevents cardiac arrest and sends high energy shocks to heart