Physics 2 exam 2

Capacitors

A device whose purpose is to the store electric energy that can be released

what are capacitors made up of, what are they sperated by

-made of up 2 capacitors; spereated by insulator

charging capactior

e- transfored from one capactior to another

Does seris increase capacitance ? What about parallel

seris decrease capacitance, parallel doesnt

electric current

charges in motion

what is current desnity

AMOUNT OF CURRENT FLOWING though a certain area (Current/area)

current density

-number of charge carriers * value of charge * drift velocity

Direction of current:

-which way does it flow

-flow opposite of motion of elcelctrons

-defined as positive from higher to lower potential

Batteries

electric field set charges in motion

-electric field created by potential difference

Potential difference provideds the electric field that ___

push charges (electrons) thorugh a circut

Closed Ciruct:

-switch open or closed

-rule for current

-energy conversion

-rule for current flow

-switch is closed

-current flows all the way through

-electrical energy converted into light energy

-current flows downhill from higher to lower potential

Short Circut:

-resistance

-current

-clsoed or open

-little to no resistance

-current is dangerously high

-also a closed circut

Ohms law:

-what hapepdns to current

-changes linearly due to different voltages

why conductors obey ohms law

because elctrons move linerly thorugh metallic conductors

Relationship between current and voltage

-direct relationship

-therefore currnet shouldnt be constant for given voltage

Conductors are empty space(t/F)

false

Resistivity

-definition

-effect on shape

Property of metal that tells how strongly it resist the flow of electric current

-doesnt change shpae or size

low resistivity

materials lets electricity flow easily

high resistivity

matertials resist the flow of electricty

strain definition

deformation of a material when force is applied

chagnes when strain is applied:

-what happedns to length

-what happends to cross sentional area

-what happends to relativity

-length increases

-cross sentional area decreases

-relativity stay the same

Strian Gauges

thin wire or foil pattern bounded to the surface

reisatance and temperature

-relationship between 

-how does it act with cold and hot temperaure

-direct relationship

-resistance drops with cold and rises with heat

R=

Ro=

infinty=

change T =

R = resistance at temperature T

Ro= resistance at reference temperature T

infinity = termperature coefficient

change T —> T-To

what does the reistance formula assume

material behave lineraly and temperayire isnt large

Voltanic Battery

converts chemical energy into electrical using 2 different metals and electroytle

Anode —>

cathode—>

electroylte—>

1)The metal that loses electrons (oxidation)

2)the metal that gains reduction

3) solution allows ions to move and complete the circut

Voltanic battery:

-which way does current flow

-negative to the positive terminal (uphill)

Electromotive force

-energy provided per unit charge by power source

-voltage a power source gives when no current is flowing (open circt)