Notesale: Turn your study into money

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1st SEMESTER FINAL STUDY GUIDE

Below is a list of concepts you should be prepared to explain on the exam
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Saturday- Unit 1 Questions
Sunday

Equations:

Constants and conversions:

v = ​λ​ f

c = 3
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8 m/s2

v = at

G = 6
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50 x 108 km

a = ∆v / t

1 pc = 3
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46 x 1012 km

weight = m a

h = 6
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Modern civilization build on science; uses all forms of technology from space
travel to medicine
Def
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- Deals only w/ hypotheses that are testable → restricted to observable natural
world
- Scientific methods→ no way of accounting testimonies involving the supernatural
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Philosophical and religious questions
- Rely on subjective personal experience
- Do not lead to testable hypotheses
- Lie outside the realm of science
Explain how science can be correct and still be tentative
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- Facts → hypothesis → testing → theory → predictions
- Facts
- Observations about the world around us

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- Scientific fact→ competent observers can observe and agree to be true
Hypothesis
- A proposed explanation for a phenomenon made as a starting point for
further investigation
- Something you test; can be confirmed
Theory
- A synthesis of facts and well tested hypotheses; foundation of science
- With enough hypotheses that have been confirmed, it can be turned into a
theory
- A well-sustained explanation through the scientific method and repeatedly
tested and confirmed through observation and experimentation
- The way we know something works
- Allows us to make predictions about how something is, or how they WILL
be
Extra: LAW
- Repeatedly tested hypothesis
- A statement based on repeated experimental observations that describes
some phenomenon of nature
- Usually using math of how something happens
- Doesn’t tell us why something happens

Identify independent variables and dependent variables
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Trying to find how the color of
light affects plant growth
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Controlled variable ⇒ have nothing done to it
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Explain the concept of measuring
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- precision of tool
- ruler
- m- ex) 1
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Use dimensional analysis to convert units in the metric system
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Unit 2: Cosmic Evolution
● Be able to determine the number of protons, electrons and neutrons in an atom
using the periodic table
○ Protons
■ Atomic number
○ Electrons
■ Atomic number (if neutral)
○ Neutrons
■ mass # - # of protons
Understand how isotopes differ from each other and determine how many protons and
neutrons are in specific isotopes
○ proton and electron # remain the same
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● Be able to read atomic symbols and name isotopes if given the atomic mass
● Explain how light/energy is emitted or absorbed by atoms
○ Explain the properties of light as a wave
○ distinguish between emit, absorb, reflect, refract
● Explain waves
○ calculate frequency, speed, wavelength & energy using Plank’s constant
○ a disturbance that travels through a medium from one location to another
location
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● Determine velocity, acceleration and distance for free falling bodies
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81 ms^2
○ d=at^2
● Explain Newton’s three laws of motion (inertia, force, action, reaction)
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● Distinguish between mass and weight
● Describe the relationships between variables-(direct and inverse)
● Understand the organization of cosmic objects
○ universe, galaxy, star, solar system, planets
● Explain parallax as a way of finding distance
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This
started the process of forming matter
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1 billion years later, stars galaxies and nebulae formed
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○ Explain how the Big Bang theory can be true and still not be considered
“fact”
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We
however do have multiple plausible pieces of information to suggest
it happened
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There are multiple reasons we think the big bang has occurred
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This
would make sense if an explosion initially happened, and shot mass out in all
directions
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This again would only be true if an absolutely massive
explosion such as the big bang occurred
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○ Explain Hubble’s law
○ Explain the Doppler Effect in terms of waves
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■ Doppler shift states when an object emitting waves is moving in a
direction, the waves scrunch together in front, and spread out
behind it
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When a galaxy is moving
towards the earth, it gives of a blue shift
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When the galaxy is

moving away from the earth, the waves elongate and it appears as
a red shift
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■ Astronomers​ use ​Doppler​ shifts to calculate precisely how fast
stars and other ​astronomical​ objects move toward or away from
Earth
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○ Be able to read spectral lines to identify the relative distances of galaxies
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● Be able to read an HR diagram & identify the general location of the types of
stars

Possible Essay Questions
1
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Using detailed
examples from this unit explain how science is “subject to change” (or open minded to
new ideas)
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2
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3
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4
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5
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6
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Describe the cycle in terms of mass,
temperature, and color
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What is meant by the phrase – “we are made up of stardust”
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8
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Describe these
using KMT, volume, density, and pressure
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How does magnetic striping provide evidence of seafloor spreading?
10
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How Atoms Produce the Spectra 
Chapter index in this window​ — — ​Chapter index in separate window 
This material (including images) is ​copyrighted!​
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Let's see how Bohr's model of the atom explains the three types of spectra
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Remember rule #3! In order to go to a ​lower​ energy orbit, the electron ​must​ lose energy 
of a certain ​specific​ amount
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The energy of photon = the difference in energy of the energy orbits (energy 
ladder rungs)
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It 
gives off a photon with energy ​E = h × f = E​2​ - E​1
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Different jumps produce photons of different energies
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The atom produces light of certain wavelengths
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The intensity depends on the density and temperature of the gas
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The photon had energy = the difference in energy of 
the energy orbits
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Therefore, the pattern 

of absorption lines is the same as the pattern of emission lines
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They make up the 
rest of the continous spectrum you see
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​ The 
photon is absorbed and electron moves to ​E2​
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Photons of other energies pass right on by without being absorbed
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The more atoms undergoing a particular absorption transition, the darker (or 
``stronger'') the absorption line
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A thermal spectrum is produced by atoms that are closely packed together
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This smears out the normally 
sharp spectral lines (they become fatter)
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The amount of smearing, or broadening, depends on the density
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Use the UNL Astronomy Education program's ​Hydrogen Energy Levels module​ to further explore 
how emission and absorption lines are created (link will appear in a new window)
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Universality of Physical Laws in Space and Time 
The pattern of spectral lines and particular wavelengths produced by an atom depend very 
sensitively on the masses and charges of the sub-atomic particles and the interactions between 
them (forces and rules they follow)
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If 
the subatomic particles had different amount of charge or mass, the pattern of lines would be 
different than what you see on the Earth
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(Hydrogen is not special in this regard---all of the other types of 
atoms produce the same pattern that is unique to that type of atom
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Recall from the first chapter that astronomy gives us a sort of time machine: when we look at 
very distant objects we see them ​as they were​ a long time ago because light, traveling at a fast but 
finite speed, has taken a long time to travel the vast distances between us and the distant 
objects
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​The fact that we see the same pattern of 
lines for a given element in light emitted by objects at any time in the universe tells us that the laws of 
physics are the same throughout time---they do not change
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We see 
the same laws of nature operating at all places and times in the universe
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Originally 
discovered by the Austrian mathematician and physicist, Christian Doppler (1803-53), this 
change in pitch results from a ​shift​ in the frequency of the sound waves, as illustrated in the 
following picture
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The intervals between waves diminish, which translates into an increase in frequency 
or pitch
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By the change in pitch of the siren, you can determine if the 
ambulance is coming nearer or speeding away
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By analogy, the electromagnetic radiation emitted by a moving object also exhibits the Doppler 
effect
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In contrast, the radiation emitted by 
an object moving away is stretched or ​redshifted​
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The Doppler Effect In Astronomy 
In astronomy, the Doppler effect was originally studied in the visible part of the ​electromagnetic 
spectrum​
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Also, because of the inverse relationship between frequency and 
wavelength, we can describe the Doppler shift in terms of ​wavelength​
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Astronomers use Doppler shifts to calculate precisely how fast stars and other astronomical 
objects move toward or away from Earth
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The spectral line 
emission, normally found at a wavelength of 21 centimeters on Earth, might be observed at 21
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This 0
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Shifts in frequency result not only from relative motion
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One is associated with 
very strong gravitational fields and is therefore known as ​Gravitational Redshift ​
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What is a Wave?
● Waves and Wavelike Motion
● What is a Wave?
● Categories of Waves
So waves are everywhere
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Consider ​a slinky wave​ as an example of a wave
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The coils of the slinky naturally assume this position, spaced equally far apart
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The particle might be moved upwards or downwards, forwards or backwards; but 
once moved, it is returned to its original equilibrium or rest position
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We can then observe this disturbance moving through the slinky 
from one end to the other
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​ A ​pulse​ is 
a single disturbance moving through a medium from one location to another location
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The repeating and periodic disturbance that moves through a 
medium from one location to another is referred to as a ​wave​
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You have perhaps heard of the phrase ​news media​
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) within our society that 
carry the news from one location to another
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The media 
doesn't make the news and the media isn't the same as the news
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In a similar manner, a wave 
medium is the substance that carries a wave (or disturbance) from one location to another
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In the case of our slinky wave, the medium through that 
the wave travels is the slinky coils
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In the case of a sound wave moving from the church 
choir to the pews, the medium through which the sound wave travels is the air in the room
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Particle-to-Particle Interaction 
To fully understand the nature of a wave, it is important to consider the medium as a collection 
of interacting ​particles​
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The interactions of one particle of the medium with the next 
adjacent particle allow the disturbance to travel through the medium
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In the 
case of a sound wave in air, the ​particles​ or interacting parts of the medium are the individual 
molecules of air
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Consider the presence of a wave in a slinky
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As the second coil becomes displaced, it begins to push or pull on the third 
coil; the push or pull on the third coil displaces it from its equilibrium position
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This process continues in 
consecutive fashion, with each individual ​particle​ acting to displace the adjacent particle
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The medium can be pictured as a 
series of particles connected by springs
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As this neighbor begins 
to move, the spring attaching this neighbor to its neighbor begins to stretch and apply a force on 
its adjacent neighbor
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There is always a force acting upon the particles that restores them to their original 
position
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In a 
water wave, each molecule of the water ultimately returns to its original position
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It is for this 
reason, that a wave is said to involve the movement of a disturbance without the movement of 
matter
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Waves are said to be an ​energy transport phenomenon​
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In a slinky wave, a person imparts energy to the first coil by doing 
work upon it
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When the first coil returns to its original position, it possesses the same amount 
of energy as it had before it was displaced
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The second coil then has a large amount of energy that it subsequently transfers to the third coil
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The third coil has received the energy of the second coil
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In this manner, 
energy is transported from one end of the slinky to the other, from its source to another location
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Consider a common phenomenon observed at a softball game - the 
collision of a bat with a ball
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The batter applies a force to the bat, thus imparting energy to the bat in the form 
of kinetic energy
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In this example, a bat is used to transport energy from the player to 
the softball
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The bat must move from its starting location to the contact location in order to 
transport energy
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A wave transports its energy 
without transporting matter
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Energy is transported through the medium, yet the water molecules are not 
transported
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The water 

has not moved from the middle of the ocean to the shore
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The gull or duck always returns to its original position
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In a water wave, energy is transported without the transport of water
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In a stadium wave, the fans do not get out of 
their seats and walk around the stadium
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In a stadium wave, each fan rises 
up and returns to the original seat
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Waves involve the transport of energy without the transport of matter
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Each individual particle of the medium is temporarily displaced and then returns to its 
original equilibrium positioned
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Like ocean waves,
sound waves something to travel through like waves through the
ocean or through a flag
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These molecules carry the sound waves by
bumping into each other, like dominoes knocking each other over
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Electromagnetic waves are
different from sound waves because they do not need molecules to
travel
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This is why astronauts on spacewalks use radios to
communicate
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Energy, a measure of the ability to do work, comes in many forms and can
transform from one type to another
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Objects in motion are examples of
kinetic energy
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WHAT ARE WAVES?
Mechanical waves and electromagnetic waves are two important ways that
energy is transported in the world around us
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Mechanical waves are
caused by a disturbance or vibration in matter, whether solid, gas, liquid, or
plasma
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Water
waves are formed by vibrations in a liquid and sound waves are formed by
vibrations in a gas (air)
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Sound waves cannot travel in the
vacuum of space because there is no medium to transmit these mechanical
waves
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Waves in a pond do not carry the water molecules from place to
place; rather the wave's energy travels through the water, leaving the water
molecules in place, much like a bug bobbing on top of ripples in water
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Magnetism can also be static, as it is in a refrigerator magnet
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These changing fields form electromagnetic
waves
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This means that electromagnetic waves
can travel not only through air and solid materials, but also through the
vacuum of space
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He noticed
that electrical fields and magnetic fields can couple together to form
electromagnetic waves
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"

Heinrich Hertz, a German physicist, applied Maxwell's theories to the
production and reception of radio waves
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His experiment with radio waves solved two problems
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Electromagnetic waves are formed by the vibrations of electric and magnetic
fields
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Once formed, this energy travels at the speed of light until
further interaction with matter
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Photons carry
momentum, have no mass, and travel at the speed of light
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How an instrument is designed to
sense the light influences which of these properties are observed
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The particle-like nature of light is

observed by detectors used in digital cameras—individual photons liberate
electrons that are used for the detection and storage of the image data
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Polarization
is a measurement of the electromagnetic field's alignment
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Think of a throwing a
Frisbee at a picket fence
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This is similar to how sunglasses are able to eliminate glare
by absorbing the polarized portion of the light
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This energy can be described
by frequency, wavelength, or energy
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Radio and
microwaves are usually described in terms of frequency (Hertz), infrared and
visible light in terms of wavelength (meters), and x-rays and gamma rays in
terms of energy (electron volts)
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FREQUENCY
The number of crests that pass a given point within one second is described
as the frequency of the wave
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A wave with two cycles that pass a point in one second has a
frequency of 2 Hz
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The distance between crests is the wavelength
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An electron volt is the amount of
kinetic energy needed to move an electron through one volt potential
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Consider a jump rope with its ends

being pulled up and down
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A light-year is the distance that light can travel in one year - that is,
in the time it takes the planet Earth to make one full trip around the Sun
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In an hour,
light travels about 670 million miles
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So in a
year, light travels about 9
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That's a lot of zeroes, so
we just shorten it and say "one light-year"
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4
light-years away
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The
whole ​universe is much, much bigger than that
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7 billion
light-years across
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It takes that long for the light to get from Alpha
Centauri to your ​eyes​
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That's how we know what the universe was like
when it was first forming, after the ​Big Bang​
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These ionic bonds are generally stronger than
covalent bonds​
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Sodium's so unstable that if you add ​water to it it catches on fire!
When those unstable atoms come near another unstable atom, they trade electrons
until they find a more stable arrangement
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For instance, when sodium atoms come near chlorine atoms, the
chlorine atoms are also very unstable, because chlorine is missing an electron to fill up

its outer ring
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Then the chlorine atom is stable, and so is the sodium atom
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The old
atoms had the same number of ​protons and ​electrons​: sodium had eleven protons and
eleven electrons, and chlorine had 17 protons and 17 electrons
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But after the reaction, the
sodium atom has one more proton than electron, so it has a weak positive charge
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Just the way a negatively charged ​magnet pulls toward a positively charged magnet, a
negatively charged atom (called a negative ion or anion) pulls toward a positively
charged atom (called a positive ion or cation)
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Most of the solid things in the universe - like ​rocks - use ionic bonds to hold themselves
together
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Like ​magnets​, any two positively charged chlorine ions will push away from
each other, and so do two negatively charged sodium ions
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So they end up arranged into a stiff crystal framework
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