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ELECTRICITY (Section 1.1 - Materials Can Become Electrically Charged…
ELECTRICITY
Section 1.1 - Materials Can Become Electrically Charged
Moving Electric Charges Transfer Energy
Electric charge is a property of matter
Electric Charge: A property that allows an object to exert force on another object without touching it.
Electric Field: The space around a particle through which an electric charge can exert force (push or pull)
Static charges are caused by the movement of electrons
Static Charge: A buildup of electric charge in an object caused by an excessive amount of one type of charge (positive or negative)
Technology uses static electricity
Example: Photocopier
Example: painting cars
Example: electrostatic air filter
Charging by contact: occurs when one material's electrons are attracted to another material more than their own
Materials in contact are charging eachother
When two uncharged object touch, electrons transfer from one to another.
Example: Neutrally charged balloon and rod
Materials higher on the list give up electrons to materials lower on the list:
Fur
Silk
Wool
Paper
Nylon
Rubber
Glass
Polyester
Skin
Example: Balloon and Hair
Example: Bunny fur and balloon
"static" originates from the Greek word Statos which means standing
PICK OUT SECTIONS, USE TITLES, HEADINGS, BOLDED/HIGHLIGHTED WORD, EQUATIONS, EXAMPLES, DEFINITIONS, ETC.
Charging By Induction
Induction:The buildup of a charge without direct contact
Can result in temporary static charge
Only occurs when one object is already charged
Can result in polarization
Charge Polarization
Polarization: A charge build up in an atom when the position of electrons changes. The electrons have moved.
Examples: Electroscope and negatively charged balloon
Materials with opposite charges attract each other
Materials with alike charges repel each other
Electric charge can be either positive or negative
Protons
Neutrons
Net Charge: the total number of excess charges (positive or negative) or unbalanced charges in an object
Measured in Coulombs
C
1C=6.24 x 10^18 e
Elementary charge (e)
smallest unit of charge
The charge on a proton or electron
Measured in coulombs
e=1.60 x 10^-19 C
Section 1.2 - Charges Can Move From One Place to Another
Static charges have potential energy
static charge can stay in a location indefinitely
static charge can move between objects
movement of a static charge out of an object is known as static discharge
Static charges move because of the force of attraction or repulsion between charged particles
Electric potential: the amount of electric potential energy per unit charge at a certain position in an electric field
volt: is equal to one joule of energy per coulomb of charge
Electric potential energy: the energy a charged particle has due to its position in an electric field
potential energy: stored energy an object has due to its position
Kinetic energy: the energy of motion
Charge Movement
the force of attraction or repulsion between charged particles is stronger when they are closer together
when the difference in electric potential between 2 charged objects is enough, it can move a charge through the air onto another object
Example: static shock or spark
Electric potential energy moves static charge from one object to another
the movement of an electric charge through a material can cause the material to heat up
example: burner of an electric stove
Lightning
a high-energy static discharge
comes from electric potential of millions of volts
releases energy in forms of:
light
heat
sound
Created from:
A. Charge separation:
particles within a cloud become electrically charged
charges are separated by wind and gravity (heavier negative charges to bottom and lighter, positive charges to top
B. Charge buildup
because of induction, negatively charged particles repel electrons in the ground
ground becomes positively charged
C. Static discharge
electric potential made of difference in charges becomes great enough
negative charges are released from the cloud, moving towards the ground
energy released makes the lightning flash and thunder sound
Materials affect charge movement
Conductor: a material that allows electric charges to move through it easily
Examples:
metals
iron
steel
copper
aluminum
has a low resistance
Insulator: a material that doesn't easily allow charges to pass through it
Examples:
plastic
rubber
air
cloth
has a high resistance
wood
Resistance: the property of a material that determines how easily a charge can move through it
measured in ohms
ohms: a unit through which electrical resistance is measured
symbol for ohms is the greek letter omega
depends on shape and type of material
Superconductors: materials that have practically no resistance at extremely low temperatures
really good conductors
examples: used in pwerlines and high-speed trains
can help save energy
can help reduce friction
would increase speed of technology
not extremely practical because they have to be kept at low temperatures
Grounding: provides a harmless , low-resistant path for electricity to follow, usually to the earth
absorbs charge and makes it harmless
Section 1.3 - Electric Current Is A Flow of Charge
Electric charge can flow continuously
Electric current: another name for a flow of charge
form of electricity used to power homes, schools and buildings
Current, voltage and resistance
steadily flowing charges have certain rates of flow
flow rate can be measured
standard unit of measure for flow charge is an ampere
also called amp
the amount of charge that flows past a given point per unit of time
electric current is amperage
compared to flow of water through a pipe
voltage and resistance determine rate of flow of electric charge
Ohm's law
Current = Voltage/Resistance
I=V/R
I is current
measured in amps
V is voltage
measured in volts
R is resistance
measured in ohms
Measuring electricity
measured using different devices
volts: measured with a voltmeter
Amps measured with an ammeter
Ohms measured with an ohmmeter
all three instruments combined in a multimeter
Electric cells supply electric current
electric cell: produced electric current using the chemical or physical properties of different materials
electrochemical cells
produces electric current through chemical reactions
example: batteries
solar cells
produce electric current by absorbing energy from the sun
example: silicon
example: solar panel
Electric cells supply electric current
Electric cell: produces electric current using the chemical or physical properties of different materials
electrochemical cells
uses chemical reactions
contains two electrodes
creates a flow of charge (electrons)
Primary cells
regular-use everyday batteries
contains chemicals
manganese dioxide
zinc
carbon
use chemical reactions until the chemicals are used up
example: regular batteries
Storage cells
example: car batteries, phone batteries
contains chemicals
lad peroxide
lead sulfate
lead
water
sulfuric cid
rechargable
chemical reactions can be reversed