Transcript Longitudinal Waves

MATTER
States of Matter
Kinetic Molecular Theory
Four States of Matter
Thermal Expansion
Kinetic Molecular Theory
• KMT
– Tiny, constantly moving particles make up all
matter.
– The kinetic energy (motion) of these particles
increases as temperature increases.
Four States of Matter
• Solids
– low KE - particles vibrate but can’t move
around
– definite shape & volume
– crystalline - repeating geometric pattern
– amorphous - no pattern (e.g. glass, wax)
Four States of Matter
• Liquids
–higher KE - particles can
move around but are still
close together
–indefinite shape
–definite volume
Four States of Matter
• Gases
–high KE - particles can
separate and move
throughout container
–indefinite shape &
volume
Four States of Matter
• Plasma
– very high KE - particles collide with enough
energy to break into charged particles (+/-)
– gas-like, indefinite
shape & volume
– stars, fluorescent
light bulbs, TV tubes
Thermal Expansion
• Most matter expands when Thermal Expansion Joint in a
heated & contracts when
Bridge
cooled.
•  Temp causes  KE.
Particles collide with more
force & spread out.
Phase Changes
• Solid to Liquid
• Liquid to Solid
Melting
Freezing
Melting point = Freezing point
Phase Changes
• Vaporization (boiling)
– liquid to gas at the boiling point
• Evaporation
– liquid to gas below the boiling point
• Condensation
– gas to liquid
Phase Changes
• Sublimation
– solid to gas
– EX: dry ice, freeze
drying, iodine
Phase Changes
Matter Flowchart
MATTER
yes
MIXTURE
yes
Is the composition
uniform?
Homogeneous
Mixture
(solution)
no
Can it be separated by
physical means?
PURE SUBSTANCE
no
Heterogeneous
Mixture
yes
Can it be decomposed by
chemical means?
Compound
Element
no
Pure Substances
• Element
– matter composed of identical atoms
– EX: copper
Pure Substances
• Compound
– matter composed of 2 or more
elements in a fixed ratio
– properties differ from those of
individual elements
– EX: salt (NaCl)
Mixtures
• Variable combination of 2 or more pure
substances.
 Homogeneous Mixture
even distribution of components
very small particles
particles never settle
EX: saline solution
Kool-Aid
Mixtures
• Heterogeneous Mixture
Soup & Salad
– uneven distribution of components
Mixtures
• Colloid
– medium-sized particles
– particles never settle
– EX: milk
Mixtures
• Suspension
– large particles
– particles scatter light
– particles will settle
(needs to be shaken)
– EX: fresh-squeezed lemonade
Chemical Symbols
• Capitals matter!
• Element symbols contain ONE capital letter
followed by lowercase letter(s) if necessary.
Co vs. CO
Element
(Cobalt)
Compound
(Carbon Monoxide )
Subatomic Particles
ATOM
ATOM
NUCLEUS
NUCLEUS
ELECTRONS
ELECTRONS
PROTONS
PROTONS
NEUTRONS
NEUTRONS
POSITIVE
CHARGE
NEUTRAL
CHARGE
Most of the atom’s mass.
NEGATIVE
CHARGE
NEGATIVE CHARGE
in a neutral atom
Atomic Number
equals the # of...
Physical Property
• A characteristic of a substance that can be
observed without changing its identity.
– can be used to separate mixtures
– EX: magnetism, density
Physical Change
• A change in the form of a substance without
changing its identity.
– properties remain the same
– reversible
– can be used to separate mixtures
– EX: dissolving, grinding
Chemical Change
• A change in the identity of a substance.
– properties change
– irreversible
– Signs: color change, formation of a gas/solid, release
of light/heat
– EX: burning, rusting
Chemical Property
• A characteristic that indicates whether a
substance can undergo a specific chemical
change.
– EX: flammability, reactivity
The Periodic Table
History of the Periodic Table
Dmitri Mendeleev
• Dmitri Mendeleev (1869, Russian)
• Organized elements by
increasing atomic mass.
• Predicted the existence of
undiscovered elements.
Henry Mosely
Modern Periodic Table
• Henry Mosely (1913, British)
• Organized elements by
increasing atomic number.
• Fixed problems in Mendeleev’s
arrangement.
Metallic Character
1
2
3
4
5
6
7
• Metals
• Nonmetals
• Metalloids
B. Table Sections
1
2
3
4
5
6
7
• Representative Elements
• Transition Metals
• Inner Transition Metals
Columns & Rows
1
2
3
4
5
6
7
• Group (Family)
• Period
Terms
• Valence Electrons
–e in the outermost
energy level
WAVES:
A way to transmit energy
Waves are defined as a periodic
disturbance that carries energy from one
place to another.
A periodic disturbance is one that
happens over and over again at regular
intervals.
.
Like a bouncing ball, the motion
repeats over and over again.
There are two kinds of waves you
should recognize.
Longitudinal or compression
waves
and transverse waves.
Longitudinal waves, like sound waves, are
mechanical waves because they must have
a material to travel through.
The material they travel through is called
the “medium”.
The medium can be any material.
Air
Rock
Water
Wood
Anything!
Sometimes longitudinal waves are referred
to as compression waves because they are
caused by a vibrating object compressing
and rarefying the atoms or molecules of
the medium.
Vibrating object
Alternating areas of compression and rarefaction in the
medium.
•By vibrating back and forth, the vibrating object
alternates between compressing and rarefying the
molecules of the medium.
Areas of compression
are high pressure areas
where the molecules
are squeezed closer
together by a vibrating
object.
Areas of rarefaction are low
pressure areas where the
vibrating object pulls the
molecules further apart.
In longitudinal waves the molecules of the medium
vibrate along with the vibrating object. Molecules of
the medium vibrate back and forth on each side of a
fixed resting point, transferring their kinetic energy
to adjacent molecules. In this way the energy is
transferred, but the molecules remain in place.
Longitudinal waves get their name because the
vibration that puts energy into the wave vibrates in
the same plane in which the energy moves.
Transverse Waves
In a transverse wave the particle displacement is
perpendicular to the direction of the energy
transfer.
The particles do not move along with the wave, they simply
vibrate up and down about their individual rest positions as the
wave passes by.
Pick a single particle and watch its motion.
The wavelength of a wave is the distance
between successive vibrations. Wavelength
is measured in meters. Here is how
wavelength is measured on a transverse
wave.
This diagram shows how wavelength can
be measured on a longitudinal wave. It
is measured from compression to
compression.
The Amplitude of a wave determines how much
energy a wave is carrying. This can easily be
seen in a transverse wave where the wave height
is the amplitude. Obviously, the higher the wave
crest the higher the amplitude, and the greater
the wave energy.
In longitudinal waves amplitude is a measure of
the degree of compression. The more compressed
the compressions are the greater the amplitude.
Low amplitude ( Less compression)
High amplitude ( greater
compression)
Wave velocity is a measure of how fast the
energy is being transferred. Wave velocity is
measured in meters per second (m/s).
Wave frequency, for a transverse wave, is a
measure of how many wave crests pass a point in one
second. Wave frequency is measured in Hertz.
1Hertz is equal to 1wave per second. If 5 waves
pass the smiley in one second, then the wave
frequency is 5Hz or 5 waves per second.
Longitudinal wave frequency is how many compressions
pass a point in one second.
Wave period, for transverse and longitudinal waves,
is the time it takes for one complete wave ( one
wavelength) to pass a point. If it takes .3seconds
for a single wave to pass the smiley then the wave
period is .3s. Wave period is measured in seconds.
THE DOPPLER EFFECT AS IT APPLIES TO
SOUND WAVES
Joe hears a
low frequency
Moe hears a
higher
frequency
Waves
• Two Types:
Longitudinal
Transverse
C. Longitudinal Waves
• Longitudinal Waves (a.k.a. compressional)
– medium moves in the same direction as wave
motion
C. Longitudinal Waves
• Wave Anatomy
compression
rarefaction
wavelength
wavelength
Amount of compression corresponds to amount of energy  AMPLITU
Measuring Waves
• Frequency ( f )
– # of waves passing a
point in 1 second
– Hertz (Hz)
shorter
wavelength 
higher frequency
 higher energy
1 second
Speed of Sound
• 344 m/s in air at 20°C
• Depends on:
– Type of medium
• travels better through liquids and solids
• can’t travel through a vacuum
– Temperature of medium
• travels faster at higher temps
Human Hearing
sound wave
vibrates ear drum
amplified by
bones
converted to
nerve impulses in
cochlea
Human Hearing
• Pitch
– highness or
lowness of a
sound
– depends on
frequency of
sound wave
– human range: 20
- 20,000 Hz
ultrasonic waves
subsonic waves
Human Hearing
• Intensity
–volume of sound
–depends on energy (amplitude) of
sound wave
–measured in decibels (dB)
Seeing with Sound
• Ultrasonic waves - above 20,000 Hz
Medical Imaging
SONAR
“Sound Navigation Ranging”
A. EM Radiation
• Electromagnetic Radiation
– transverse waves produced by the motion of
electrically charged particles
– does not require a medium
– speed in a vacuum = 300,000 km/s
– electric and magnetic
components are
perpendicular
EM Radiation
• Photons
– tiny, particle-like bundles of
radiation
– absorbed and released by
electrons
energy increases with
wave frequency
EM Spectrum
long 
short 
low f
high f
low
energy
high
energy
Types of EM Radiation
• Radiowaves
– lowest energy EM radiation
Types of EM Radiation
• Radiowaves
– FM - frequency modulation
– AM - amplitude modulation
Microwaves
penetrate food and vibrate
water & fat molecules to
produce thermal energy
Types of EM Radiation
• Infrared Radiation (IR)
– slightly lower energy than visible
light
– can raise the thermal energy of
objects
– thermogram - image made by
detecting IR radiation
Types of EM Radiation
• Visible Light
– small part of the
spectrum we
can see
– ROY G. BIV colors in order
of increasing
energy
R
red
O
Y
orange yellow
G.
green
B
blue
I
indigo
V
violet
Types of EM Radiation
• Ultraviolet Radiation (UV)
– slightly higher energy than visible light
– Types:
• UVA - tanning, wrinkles
• UVB - sunburn, cancer
• UVC - most harmful,
sterilization
Types of EM Radiation
• Ultraviolet Radiation (UV)
– Ozone layer depletion = UV exposure!
Types of EM Radiation
• X rays
– higher energy than UV
– can penetrate soft tissue, but
not bones
Types of EM Radiation
• Gamma rays
– highest energy
EM radiation
– emitted by
radioactive atoms
– used to kill cancerous
cells
Radiation treatment using
radioactive cobalt-60.
Light and Matter
• Opaque
– absorbs or reflects all light
• Transparent
– allows light to pass through completely
• Translucent
– allows some light to pass through
Seeing Colors
• The retina contains…
Stimulates red & green cones
– Rods - dim light, black & white
– Cones - color
• red - absorb red & yellow
• green - absorb yellow & green
• blue - absorb blue & violet
Stimulates all cones
Mixing Colors
• Primary
light colors
– red, green, blue
– additive colors
– combine to form white light
EX: computer RGBs
View Java Applet on primary light colo
Mixing Colors
• Filter
– transparent material
that absorbs all light
colors except the filter
color
View Java Applet on filters.
Mixing Colors
• Pigment
– colored material that absorbs
and reflects different colors
• Primary pigment colors
– cyan, magenta, yellow
– subtractive colors
– combine to form black
EX: color ink cartridges
C. Mixing Colors
Light
Pigment
When mixing pigments, the color of the mixture is the color
of light that both pigments reflect.
Reflection
Normal
• Reflection
incident beam
– when a wave strikes
an object and bounces
off
reflected beam
Reflection
• Law of Reflection
– the angle of
incidence equals
the angle of
reflection
Refraction
• Refraction
SLOWER
– bending of waves when passing from
one medium to another
– caused by a change in speed
• slower (more dense)  light bends toward
the normal
FASTER
• faster (less dense)  light
bends away from the normal
Refraction
• Refraction depends on…
– speed of light in the medium
– wavelength of
the light - shorter wavelengths
(blue)
bend more
Refraction
• Example:
Diffraction
• Diffraction
– bending of waves around
a barrier
– longer wavelengths (red)
bend more - opposite of
refraction
D. Interference
• Interference
– constructive  brighter light
– destructive  dimmer light
Cool Applications!
• The “Broken Pencil”
– refraction
E. Cool Applications!
• Diffraction Gratings
– glass or plastic made up of
many tiny parallel slits
– may also be reflective
– spectroscopes, reflective
rainbow stickers, CD surfaces
Motion & Forces
Motion
 Speed & Velocity
 Acceleration

Newton’s First Law
• Newton’s First Law of Motion
– An object at rest will remain at rest and an
object in motion will continue moving at a
constant velocity unless acted upon by a net
force.
Motion
• Motion
– Change in position in relation to a reference point.
Reference point
Motion
Speed & Velocity
d
• Speed
– rate of motion
– distance traveled per unit time
v t
distance
speed 
time
Speed & Velocity
• Instantaneous Speed
– speed at a given instant
• Average Speed
total distance
avg. speed 
total time
Speed & Velocity
• Velocity
– speed in a given direction
– can change even when the speed is constant!
Acceleration
• Acceleration
– the rate of change of velocity
– change in speed or direction
a
v f  vi
t
vf - vi
a t
a: acceleration
vf: final velocity
vi: initial velocity
t: time
Acceleration
• Positive acceleration
–“speeding up”
 Negative
acceleration
 “slowing down”
Graphing Motion
Distance-Time Graph
A
• slope = speed
• steeper slope =
faster speed
B
• straight line =
constant speed
flat line = no motion
Graphing Motion
Distance-Time Graph
• Acceleration is
indicated by a curve
on a Distance-Time
graph.
400
Distance (m)
300
200
• Changing slope =
changing velocity
100
0
0
5
10
Time (s)
15
20
Motion & Forces
Force & Acceleration

Newton’s Second Law
 Gravity
 Air Resistance
 Calculations
Newton’s Second Law
• Newton’s Second Law of Motion
– The acceleration of an object is directly
proportional to the net force acting on
it and inversely proportional to its mass.
F = ma
A. Newton’s Second Law
F
a
m
F = ma
F
m a
F: force (N)
m: mass (kg)
a: accel (m/s2)
1 N = 1 kg ·m/s2
Gravity
• Gravity
– force of attraction between any two
objects in the universe
– increases as...
• mass increases
• distance decreases
Gravity
• Who experiences more gravity - the
astronaut or the politician?
 Which exerts more gravity the Earth or the moon?
less
distance
more
mass
Gravity
• Weight
– the force of gravity on an object
W = mg
W: weight (N)
m: mass (kg)
g: acceleration due
to gravity (m/s2)
MASS
WEIGHT
always the same
(kg)
depends on gravity
(N)
Gravity
• Would you weigh more on Earth or
Jupiter?
 Jupiter because...
greater mass
greater gravity
greater weight
B. Gravity
• Accel. due to gravity (g)
 In the absence of air
resistance, all falling objects
have the same acceleration!
 On Earth: g = 9.8 m/s2
W
g
m
elephant
g
W
m
feather
Air Resistance
• Air Resistance
– a.k.a. “fluid friction” or “drag”
– force that air exerts on a moving
object to oppose its motion
– depends on:
• speed
• surface area
• shape
• density of fluid
• Is the following statement true or false?
– An astronaut has less mass on the moon
since the moon exerts a weaker
gravitational force.
 False! Mass does not depend on
gravity, weight does. The astronaut has
less weight on the moon.
Newton’s Third Law
• For every action, there is an
equal and opposite reaction.
Other examples of Newton’s Third Law
• The baseball
forces the bat to
the left (an
action); the bat
forces the ball to
the right (the
reaction).
3rd Law
The reaction of a rocket is
an application of the third
law of motion. Various
fuels are burned in the
engine, producing hot
gases.
The hot gases push against
the inside tube of the rocket
and escape out the bottom
of the tube. As the gases
move downward, the rocket
moves in the opposite
direction.
- What Is Energy?
Kinetic Energy
• Kinetic energy increases as mass and velocity
increases.
- What Is Energy?
Potential Energy
• Gravitational potential energy increases as
weight and height increase.
- Energy Transformations and Conservation
Energy Transformations
• Most forms of energy can be transformed into
other forms.
- Energy Transformations and Conservation
Transformations Between
Potential and Kinetic Energy
• A pendulum continuously transforms energy
from kinetic to potential energy and back.
- Energy and Fossil Fuels
Use of Fossil Fuels
• Fossil fuels can be burned to release the
chemical energy stored millions of years ago.
Multiple Choice
Identify the choice that best completes the statement or
answers the question.
1) The total potential and kinetic energy of the
particles in an object is called
a. mechanical energy.
b. thermal energy.
c. chemical energy.
d. electrical energy.
Multiple Choice
Identify the choice that best completes the statement or
answers the question.
2) An example of something that stores chemical
energy is
a. lightning.
b. a microwave.
c. a match.
d. light.
Multiple Choice
Identify the choice that best completes the statement or
answers the question.
3) What type of conversion is taking place when
natural gas is used to heat water?
a. chemical energy into thermal energy
b. thermal energy into mechanical energy
c. mechanical energy into electromagnetic
energy
d. electromagnetic energy into chemical energy
Multiple Choice
Identify the choice that best completes the statement or
answers the question.
4) When you rub your hands together on a cold
day, you use friction to convert
a. mechanical energy into thermal energy.
b. thermal energy into nuclear energy.
c. nuclear energy into electrical energy.
d. electrical energy into electromagnetic energy.
Multiple Choice
Identify the choice that best completes the statement or
answers the question.
5) According to the Law of Conservation of Energy,
when energy changes from one form to another
form, the total energy of that system ___
a. increases.
b. alternates.
c. decreases.
d. remains the same.
Multiple Choice
Identify the choice that best completes the statement or
answers the question.
6) What energy
transformations take
place in a Hydroelectric
power plant?
A) ME C EM T
S
B) E ME EM T
C) ME E
D) GPE KE ME E
Multiple Choice
Identify the choice that best completes the statement or
answers the question.
7) What are the energy transformations that take place in a
coal burning power plant in order from the starting energy
form to the end product?
A) Electrical to Mechanical to Thermal to Chemical
B) Chemical to Thermal to Mechanical to Electrical
C) Mechanical to Thermal to Chemical to Electromagnetic
D) Mechanical to Chemical to Thermal to Mechanical
Multiple Choice
Identify the choice that best completes the statement or
answers the question.
8) What type of energy transformations takes place
during photosynthesis?
A)
B)
C)
D)
Electromagnetic
Electromagnetic
Electromagnetic
Electromagnetic
to
to
to
to
Electromagnetic
Thermal
Chemical to Thermal
Sound
Multiple Choice
Identify the choice that best completes the statement or
answers the question.
9) What
energy transformations take place in the
picture above in order from start to the end
product?
A.
T
C.
ME
B.
ME
D.
MEET
Multiple Choice
Identify the choice that best completes the statement or
answers the question.
10) Which is not a renewable fuel source?
A. Geothermal
B. Coal
C. Wood
D. Solar
Graphic Organizer
Energy
exists as
Kinetic energy
measured in
is the ability
to do
Joules
Work
Potential energy
which at a given
rate is
can be
Elastic
Gravitational
Power
What is thermal energy?
S8P2d. Describe how heat can be transferred
through matter by the collisions of atoms
(conduction) or through space (radiation).
In a liquid or gas, currents will facilitate the
transfer of heat (convection).
What is Thermal
Energy?
Kinetic Theory of Matter
1. All matter is made of atoms and molecules that act like
tiny particles.
2. These tiny particles are always in motion. The higher the
temperature, the faster the particles move 􀃆 (The higher
the temperature, the more KE due to speed at which the
particles move)
3. At the same temperature, more massive (heavier) particles
move slower than less massive (lighter) particles. (Mass and
Velocity of particle movement are inversely proportional. If
temp remains the same, mass will have to increase if
velocity decreases and vice versa)
Particles of matter are in constant motion. This
motion relates directly to the state of matter of the
object (solids, liquids, or gases).
Temperature affects how fast these particles move.
The higher the temperature the faster the particles
move. Moving particles possess kinetic energy.
Temperature is defined at the average kinetic energy
of the particles of an object.
Thermal Energy is the sum total of all of the energy of
the particles of an object.
Thermal energy and temperature are related though
DIFFERENT.
Temperature is the average kinetic energy of the
particles of an object.
Thermal energy is the total amount of energy of the
particles of an object.
A bathtub full of water at 100oF has more thermal
energy than a thimble of water at 100oF. The
temperature is the same but the total amount of
energy is different. The bathtub has more energy.
Transferring Thermal Energy
How is Thermal Energy Transferred? YOU MUST
KNOW THIS!!!!!
Conduction – direct contact
Convection – through a fluid
Radiation – by electromagnetic waves
What is heat transfer by conduction?
Heat transfers as particles of an object increase their
collisions as heated. These collisions transfer the heat
energy through the object by colliding with nearby
particles.
What is heat transfer by convection?
Heat is transferred through a substance through
currents. This occurs in fluids (liquids AND gases)
Convection currents are caused by heating of a liquid
or gas, the liquid or gas rises, then cools and falls. This
occurs in the mantle of the earth
And in the atmosphere.
Most of our weather patterns are the result of
convection currents in the atmosphere.
What is heat transfer by radiation?
Radiation is heat transfer by electromagnetic waves.
These wave may pass through all states of matter and
also through NO matter – such as the vacuum of
space.
This energy is often called radiant energy.
Radiant energy from the sun travels through the
vacuum of until it reaches the earth.
How is heat flow controlled?
Insulators – a material which does not allow heat to
pass through it easily.
Some animals have good
insulation to survive
severe winters.
Buildings and houses are insulated so that heat does
not pass out of (winter time) and into (summer time).
What are some other uses of insulation?
1) Conduction is the transfer of energy by
A) molecules bumping into each other
B) the difference of density
C) the traveling of waves
D) convection currents moving
2) What is it called when cold air falls down and
warm air pushes up?
A) convection
B) conduction
C) radiation
D) insulation
3) Which is the best example of conduction?
A) You take a sip of hot soup and burn your tongue.
B) Water in a well-built thermos takes hours to cool.
C) You get a sun burn from sitting in the sun all day.
D) You swim in a lake and notice in some areas, the
water is warm but in others it's cold.
4) Which is the best example of convection?
A) You get a sun burn from sitting in the sun all day.
B) You take a sip of hot soup and burn your tongue.
C) Water in a well-built thermos takes hours to cool.
D) You swim in a lake and notice in some areas, the
water is warm but in others it's cold.
4) Which is the best example of radiation?
A) You get a sun burn from sitting in the sun all day.
B) You take a sip of hot soup and burn your tongue.
C) Water in a well-built thermos takes hours to cool.
D) You swim in a lake and notice in some areas, the
water is warm but in others it's cold.
5) The total energy of all the particles in a substance
is called
A. temperature.
B. thermal energy.
C. degrees.
D. mass.
6) Heat, like work, is an energy transfer measured in
A. watts.
B. degrees.
c. joules.
d. kelvins.
7) The movement of thermal energy from a warmer
object to a cooler object is called
A. heat.
B. temperature.
C. motion.
D . momentum.
8) A material that does NOT conduct heat well is
called a(an)
a. insulator.
b. conductor.
c. metal.
d. radiator.
9) The addition or loss of thermal energy changes
the arrangement of the particles during
a. a change of state.
b. conduction.
c. convection.
d. radiation.
10) Which of these is a good conductor?
a. Wood
b. Paper
c. Silver
d. Air
11) You have four containers of water. The
water in each container is at the same
temperature. Which container has the
greatest thermal energy?
A. a 5-mL container
B. a 10-mL container
C. a 15-mL container
D. a 50-mL container
Electric Currents
An electric current is a flow of electric charges.
A circuit is the path that
is made for an electric
current.
Series Circuit
• A circuit that only has one path
for current to flow through is
called a series circuit.
If the path is broken, no
current flows through the
circuit.
Parallel Circuits
• A type of circuit that has more than
one path for current is called a
parallel circuit.
If one part of the path is
removed, the current
continues to flow through
the other paths of the
circuit.
Circuit symbols
• A battery (the correct
name for this is a cell)
Circuit symbols
Circuit symbols
• A connector (or wire)
Circuit symbols
•
a bulb
Circuit symbols
A
•An ammeter
Circuit symbols
V
Circuit symbols
V
• a voltmeter
Circuit symbols
• a resistor
Electricity
A. Electric Charge
1. Static electricity is the
accumulation of excess electric
charges on an object.
a. More e¯ = negative charge
b. More protons = + charge
2. Charge is conserved (e¯ move
from one object to another).
3. Law of Charges
a. Opposite charges
attract.
b. Like charges repel.
4. Electric fields
a. Electric fields exert force on
objects within the field.
b. Weaker with distance.
5. Transferring electric charge
a. Conductors: e¯ move easily.
b. Insulators: hold e¯ tightly.
c. Contact charging is
done when two materials
are rubbed together (best
with insulators).
d. Charging by induction is
done when one charged object
induces a charge on another.
6. Lightning
a. Large static
discharge between the
earth and clouds.
b. Lightning was found
to be static electricity by
Ben Franklin.
7. Grounding
a. Conductive path to Earth.
b. Lightning rods & plumbing.
e. Wire resistance greater for:
1) Longer wires
2) Thinner wires
3) Higher temperatures
C. Electrical Circuits
1. A circuit is a conducting path.
2. Series circuit
a. One path
b. Any break &
all devices go out
c. Current is the same
throughout the circuit
3. Parallel circuit
a. Multiple paths
b. A break in one
branch & the other
branches stay on
c. Voltage is the same in each
branch, but current and
resistance may be different
Comparison of series and parallel
circuits
The same
voltage battery
Notice the
brightness of
the bulbs
- What Is Magnetism?
Magnetic Fields
• Magnetic field lines spread out from one pole,
curve around the magnet, and return to the
other pole.
- What Is Magnetism?
Magnetic Fields
• When the magnetic fields of two or more
magnets overlap, the result is a combined
field.
- Inside a Magnet
The Atom
• An atom contains neutrons and positively
charged protons in its nucleus. Negatively
charged electrons move randomly throughout
an atom.
- Inside a Magnet
Magnetic Domains
• In a magnetized material, all or most of the
magnet domains are arranged in the same
direction.
- Inside a Magnet
Making and Changing Magnets
• Each piece of a magnet retains its magnetic
properties after it is cut in half.
- Magnetic Earth
Earth as a Magnet
• Just like a bar magnet,
Earth has a magnetic
field surrounding it and
two magnetic poles.
Graphic Organizer
Magnets
•
produce
Magnetic fields
strongest at
The poles
have atoms
grouped in
mapped by
Magnetic field
lines
Magnetic
domains
The End