electrostatics and electrodynamics

what is electrostatics

the study of electric charge in stationary form

when is an object electrified

when there are to manny electrons

what are methods od electrification

friction, contact, and induction

what is friction

transfer of electrons by rubbing objects together

what is contact (conduction)

transfer of electrons by touching electrified objects to another object

what charge gets transferred through contact

usually same charge; neg→neg, pos→pos

what is an electroscope

measures electrification by contact

what is induction

charged and uncharged objects do NOT touch

what charge gets transferred through induction

opposite charges

what is grounding

grounding enables more permanent charge to build up

first law of electrostatics

like charges repel opposite attract

what is coulombs law

the force between two charges is directly proportional to the magnitude of the two charges. inversely proportional to the square of the distance between the object

where is the distribution of charge

over outer surface only of a dense conductor or a hollow object

what is the concentration of charge

concentrated at sharpest curves on irregular objects

what happens between lines of force and strength of field

strong fields=more lines of force(flux lines)

strong fields=closer lines of force

what is electrodynamics

the study of electric charges in motion

what is a circuit

closed loop that conducts electricity; path along which electrons can move

what is a conductor

allows electrons to flow (water, metal, tissue)

what is a insulator

nonconductor, dielectric; inhibits the flow of electrons (rubber)

what is a semi conductor

acts as both a conductor and an insulator (silicon)

what is a superconductor

allows electrons to flow without resistance (titanium, very very cold environments)

what is the components of a circuit

current (amperage, I), potential differnece (voltage, V), resistance (ohms, R, Ω)

what is the unit of current

ampere= charge/time

what is potential difference

electromotive force (voltage), force that causes charges to move; electrical push or pull

how will electrons flow

if potentials are connected by a conducting path electrons will flow from high to low (neg→pos)

what is resistance

anything that opposes or limits a current

what is the amount of R dependent on

material, length of path, cross section area, and temperature

how does material affect R

conductor (low R, flow freely) vs insulator (high R, impedes flow)h

how does the length of the path affect the R

R increases with length

how is R affected in a cross sectional area

R increases with the decrease of cross section

how does temperature affect R

as temp increases R increases

what is voltmeters

measures potential differences and is connected across load (parallel connection)

what is anmeter

measures current and is connected in path so all electrons pass through it (series connection)

what is ohms law

voltage in a circuit will be equal to the current times the resistance

what is electric power

amount of work that a circuit can do

what is the rate of change in electrical energy formula

p=v•I

what is the power using I and R formula

P=I²•R

what is a direct current

electrons flow in 1 direction through the circuit path; steady and pulsed

what is an alternating current

electrons flow one way then the opposite way; sine wave

what is a capacitor

a device that temporarily stores charge in an electric circuit

what is a capacitance

ratio of charge stored to potential difference between plates; the unit of charge that is stored in a capacitor