6th Grade Science

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6th Grade Science

• This presentation consists of important
  information discussed in science class. While
  students should take advantage of using this
  resource at home, it will not be updated
  everyday. Students are expected to use the notes
  taken in class as a primary source of
  information.

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Genetics

• Traits- characteristics
• Heredity- passing of traits from parents to
  offspring
• Genetics- the scientific study of heredity

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Gregor Mendel

• The Father of Genetics
• Studied pea plants and found that recessive
  traits can be masked by dominant traits, but they
  do not disappear. The recessive traits can be
  carried along in the genes and show up in future
  generations.
• Dominant-stronger allele (always shows up if
  present)
• Recessive-weaker allele (masked or hidden by
  dominant allele and only shows up when there is
  no dominant allele present)
• Homozygous/Purebred- 2 of the same alleles (TT or
  tt)
• Heterozygous/Hybrid- 2 different alleles (Tt)

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The Cell

• The basic unit of life.
• The human body contains trillions of cells.
• The cell contains a nucleus.
• The nucleus contains chromosomes.
• Chromosomes contain DNA.
• Genes are segments of DNA that code for specific
  traits.

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Parts of the Cell

• Cell Membrane- controls what goes in and out of
  the cell
• Nucleus- control center
• Endoplasmic Reticulum- transports material
  throughout the cell
• Ribosomes- make proteins
• Golgi Bodies- receive, sort, and send out
  materials to other parts of the cell
• Lysosomes- break down waste
• Vacuole- stores food, water, and waste
• Mitochondria- powerhouse (creates energy for
  the cell)
• Cytoplasm- gel-like material that contains the
  different organelles.
• Centrioles- pull apart cells for cell division
• Chloroplast- uses sunlight to make food for
  plant cells
• Cell Wall- the rigid wall on the outside of
  plant cells

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DNAJames Watson and Francis Crick discovered the
double helix structure of DNA

• Deoxyribonucleic Acid
• D Deoxyribose Sugar
• N In the nucleus
• A Acid
• Nitrogen Bases (Steps of the Ladder)
• Adenine-Thymine
• Cytosine-Guanine
• Phosphates and Sugars (Sides of the Ladder)
• Genes- factors that control traits (hair color)
• Alleles- different forms of genes (brown)

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Chromosomes

• Human cells contain 23 pairs of chromosomes, a
  total of 46.
• Each pair contains one from mom and one from dad.
• The genes are located on the chromosomes and
  these genes code for specific traits.
• Stronger Trait-Dominant
• Weaker Trait-Recessive
• 2 Dominant TraitsHomozygous Dominant
• 2 Recessive TraitsHomozygous Recessive
• 1 Dominant and 1 RecessiveHeterozygous (Dominant
  Trait will show up)
• Genotype-genetic makeup/allele combination
• Phenotype-physical appearance/visible trait

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DNA Replication

• In order for Mitosis (cell division) to occur,
  each chromatid must make a copy of its DNA so
  that each new cell has the same genetic
  information.
• Steps
• DNA double helix unzips
• Floating Nitrogen Bases in the nucleus match up
  with Nitrogen Bases on the DNA strands.
• 2 identical DNA molecules are formed, which is 2
  identical sister chromatids, or one chromosome.

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Cell Division Mitosis

• Interphase
• Cell grows to its mature size
• DNA and cell parts make copies of themselves
• Cell prepares to divide
• Mitosis
• Prophase, Metaphase, Anaphase, Telophase
• -The nuclear membrane break down
• -Chromatin condenses to form chromosomes
• -Chromosomes line up in the center of the cell
• -Chromatids separate and go to different sides
• -Two new nuclear membranes form around the
  chromatids as the cell stretches
• Cytokinesis
• The cell membrane pinches together in the center
  of the cell and the cell brakes into two
  identical cells.

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Meiosis

• Cell division that results in cells with half the
  number of chromosomes (23). These cells are
  important for reproduction, since a new baby will
  need 23 chromosomes from each parent.
• Chromosome pairs line up in the center of the
  cell and separate to different cells. Those
  cells then go through a second division, much
  like Mitosis, resulting in cells with 23
  chromosomes. The baby will then have 23 pairs of
  chromosomes, or 46 total.
• A karyotype is a picture of all the chromosomes
  in a cell. It reveals the gender of the baby
  (XXGirl and Xy Boy) and the number of
  chromosomes in the cell.

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Probability and Punnett Squares

• Probability- the chances of something happening
• Punnett Square- a tool/chart used to predict the
  probability of all the possible allele
  combinations that could result from a genetic
  cross.
• Ex. One parent is homozygous recessive with blue
  eyes and the other is heterozygous with brown
  eyes. What is the probability that the offspring
  would have blue eyes?
• B b
• b
• b
• There is a 50 chance the offspring will have
  blue eyes since 2/4 boxes show bb.

Bb bb
Bb bb
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Human Inheritance

• Phenotype-physical trait (Brown Eyes)
• Genotype-allele combination (Bb)
• Codominance-2 alleles are equally dominant (both
  show up) Ex. AB blood type
• Male (Xy) Female (XX)
• Sex-Linked Traits-traits whose genes are on the X
  or y chromosome
• Pedigree-a family tree that traces the presence
  of a traits in past generations
• Single Genes-trait is controlled by one gene
  (Widows Peak)
• Many Genes- trait is controlled by more than one
  gene (Height)
• Multiple Alleles- some genes have more than two
  alleles
• (Blood Type and Hair Color)

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Genetic Disorders
Cystic Fibrosis    
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Sickle Cell Disease    
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Hemophilia      
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Down Syndrome    
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Advances in Genetics

• Selective Breeding- the process of selecting a
  few organisms with desired traits to serve as
  parents for the next generation.
• -Inbreeding- crossing two individuals that
  have identical or similar sets of alleles.
• -Hybridization- breeding two genetically
  different individuals, in order to have the
  offspring receive the best traits from both
  parents.
• Cloning- making an organism who is identical to
  another.
• Genetic Engineering- genes from one organism are
  transferred into the DNA of another organism.
• -gene splicing- DNA molecule is cut open and
  a gene from another organism is spliced into it.
• Gene Therapy- inserting working copies of a gene
  directly into the cells of a person with a
  genetic disorder.
• DNA Fingerprinting- fingerprints found at a
  crime scene are used to help identify the person
  responsible for the crime. DNA samples come
  from Blood, Skin, or Hair.
• -Only identical twins have the same DNA, but
  their fingerprints are different.

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Tools in Genetics

• Amniocentisis- a technique by which a small
  amount of fluid that surrounds the baby is
  removed so that the chromosomes can be studied.
  This will then be used for a karyotype.
• Karyotype- a picture of all of the chromosomes
  in a cell. (Determines if the baby will be a boy
  or girl and if the baby has the right number of
  chromosomes)
• Punnett Square- a chart that shows all of the
  possible allele combinations that could result
  from a genetic cross and the probability of each
  combination.
• Pedigree- a chart or family tree that tracks
  which members of a family had or have a
  particular trait.
• Genetic Counselors- Professionals who use the
  tools above to help couples understand what
  traits can be expected when they have an
  offspring. Ex. genetic disorders

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Nature of Science
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The Goal of Science
To understand the world around us
A scientific law (fact) results from a theory
(logical explanation) being tested over and over
by scientists.
The Branches of Science
Life
Earth
Physical
Geology
Chemistry
Biology
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Problem Solving
Scientific Method a systematic approach to Problem Solving Serendipity a fortunate discovery made by accident
Steps

• 1. Question Use affect to separate the
  manipulated and responding variables
• 2. Hypothesis If, then, because
• 3. Materials Be specific!
• 4. Procedure Step by step
• 5. Observations Graphs and Charts
• Conclusions Answer question/Did you prove your
  hypothesis?

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Experimental Components
Control Setup setup without the variable
Experimental Setup setup with the variable
Manipulated Variable factor being tested
Responding Variable measurable factor being
affected by the manipulated variable Constants
factors kept the same in both setups Unwanted or
Hidden Variables-variables that we do not plan
for that may affect our results (sometimes
uncontrollable)
Example Question How does the amount of
sunlight affect the lifespan of a plant? Example
Hypothesis If the plant gets more sunlight,
then it will live longer, because sunlight gives
off energy.
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The Metric System
The standard system of measurement used by
scientists.
Advantages Universal Base 10 Predictable Prefixes Accurate and Precise Units Length-meter Volume-Liter Mass-Gram Temperature-Celsius
Kilo Hecto Deka Meter Deci Centi Milli 1000m 100m 10m 1m .1m .01m .001m Kilo Hecto Deka Meter Deci Centi Milli 1000m 100m 10m 1m .1m .01m .001m
The Metric Family
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Steps to Converting

• Underline the unit you know
• Put your pencil on the unit on the chart
• Loop from the unit you know to the unit you need
  to know
• Put your pencil on the decimal point in your
  number
• Move the decimal point the number of loops and in
  the direction you did on the chart.
• Remember If the decimal point does not show up,
  it goes to the end of the number!

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Metric Units
Length Definition The distance from one point to another Standard Unit Meter Tools meter stick, ruler Mass/Weight Definition Mass is the amount of matter in an object and weight is the amount of gravity pulling an object toward earth. Standard Unit Gram Most commonly used Kilogram Tools Triple beam balance, scale Volume Definition The amount of space an object takes up Standard Unit Liter Tools graduated cylinder, beaker, measuring cup, syringe Temperature Definition The measure of hotness or coldness Standard Unit Celsius Tool thermometer
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Graphing
Temperature Line Graph
Remember
Y
Title X and Y Axis Labels Equal Intervals Key
Temperature (Degrees Celsius)
Time (Minutes)
X
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Temperaturein Celsius

• 100 Degrees..Boiling Point
• 80 DegreesHot Coffee
• 50 DegreesHot Bath
• 37 DegreesNormal Body Temperature
• 21 DegreesRoom Temperature
• 0 Degrees..Freezing Point
• -15 Degrees..Snowy Day

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Floating and Sinking
Volume the amount of space an object takes
up Capacity the maximum amount a space can
hold Weight the amount of gravity pulling on an
object Displacement the space/water pushed
aside when another object takes its
place Buoyancy the upward force keeping an
object afloat Density mass per unit
volume Mass the amount of matter in an object
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Heat Transfer Heat transfer is The movement of
thermal energy from Warm to cold Conductors allow
heat to transfer through them. Ex.
metal Insulators do not allow heat to transfer
through them. Ex. wool
Types of heat transfer
Conduction Convection
Radiation Direct contact
Indirect contact the sun or
electromagnetic waves
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Motion, Forces, and Energy
Motion- a change in position where an objects
distance from another object changes. Reference
Point- a place or object used for comparison to
see if an object is in motion. The most common
reference point is the Earth. Force- a push or
pull. Speed- the distance traveled in one unit of
time. Velocity- speed in a given
direction. Momentum-mass x velocity (determines
how difficult it is to stop) Acceleration- the
rate at which velocity changes (speeding up,
slowing down, or changing direction.
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Friction-the rubbing together of two
objects-causes an object to slow down or stop
Sliding Friction Rolling Friction Fluid Friction
Rubbing hands together, skiing, etc. Bike riding, bowling, etc. Swimming, diving, etc.
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Forces

• Force A push or a pull
• Balanced force equal and opposite (wrestling
  face-off)
• Unbalanced force unequal and opposite (one
  person wins)

In this case the winner is the gift!
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Newtons Laws

• 1 Inertia- An object at rest will stay at
  rest and an object in motion will stay in motion
  unless acted upon by an unbalanced force.
• 2 Force Mass X Acceleration
• (the larger the mass, the more force needed to
  make it move faster)
• 3 Every action has an equal and opposite
  reaction.

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Simple MachinesMake work easier by multiplying
your effort or changing the direction of your
force.Mechanical Advantage- the number of times
a machine multiplies your effort force (how
helpful the machine is)

• Inclined Plane
• Wedge
• Screw
• Wheel and Axle
• Pulley
• Lever

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Inclined Planea flat, slanted surface

• Advantage Allows you to use less force over a
  longer distance
• Example wheelchair ramps

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WedgeThick at one end and then tapers to a thin
edge at the other end. Two inclined planes back
to back.

• Examples knife, teeth, ax, zipper
• Advantages The longer and thinner, the easier
  it is to use.

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Screwan inclined plane wrapped around a cylinder

• Examples bolts, faucets, jar lids, light bulb
• Advantages When the threads are close together,
  it is easier, but takes longer. Effort is
  multiplied over a longer distance.

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Wheel and Axletwo circular objects that are
fastened together and rotate about a common axis.
The larger object is the wheel and the smaller
object is the axle

• Examples screwdriver, doorknob, windmill,
  steering wheel
• Advantages multiplies your force over a longer
  distance

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Pulleya grooved wheel with a rope wrapped around
it

• Fixed-attached to a structure
• Changes the direction of your force
• Moveable-attached to the object
• Multiplies your force
• Pulley System-a combination of a fixed and
  moveable pulley
• Examples flagpole, blinds

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Levera rigid bar free to rotate about a fixed
point

• First Class Lever-fulcrum in between the effort
  and load scissors, seesaw, crowbar
• Advantage changes direction of force

• Second Class Lever- load is between the effort
  and fulcrum
• -Wheelbarrow, door, nutcracker
• Advantage multiplies effort force

• Third Class Lever- effort is in between the load
  and the fulcrum
• -baseball bat, tweezers,
  fishing pole
• Advantage multiplies effort force

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Potential and Kinetic Energy

• Potential energy is stored and ready to use.
• Kinetic energy is energy in motion.
• A pendulum stores potential energy before it is
  released and uses kinetic energy as it swings.

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Pendulum Notes
Pendulum- a weight hanging freely from a fixed
point. Cycle- a system of events that occurs over
and over. System- a related set of objects
working together in one arrangement. Controlled
Experiment- a study designed with a control group
and experimental group, where all factors are
kept constant except one (manipulated
variable). Variable- a factor that changes.

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Pendulums in our Lives

• Galileos Influence
• Grandfather Clock
• Foucault Pendulum
• Metronome

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Galileo

• Who? A scientist
• What? He studied pendulums and how they move.
• When? 1602
• Where? University of Pisa, Italy
• Why? These studies lead to further inventions.
• What did he discover about pendulums?
• A Pendulum never returns to its release height.
• All pendulums come to rest.
• The cycle rate is independent (not dependent
  upon) of the weight or release height.
• The cycle rate depends on the length of the
  pendulum.
• Shorter pendulums complete cycles faster

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Grandfather Clock

• Who? Christian Huygen
• What? A clock composed of a pendulum that keeps
  precise time.
• When? 1656-1657
• Where? England
• Why? It revolutionized time-keeping by including
  minutes.
• Many of these antique clocks have been passed
  down from generation to generation.

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Foucault Pendulum
Who? JBL Foucault What? An instrument used to
show the rotation of the Earth. When?
1848-1851 Where? Paris, France. Now found in
many areas around the world. Why? It proves that
the Earth rotates. How? A cannon ball attached
to a wire made a circular pattern in the sand,
demonstrating the circular rotation of our planet.
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Metronome

• Who? Winkel and Maelzel
• What? A device that regulates sound for musical
  beats.
• When? 1814
• Where? Holland (The Netherlands)
• Why? Musicians needed a way to keep a regular
  tempo.
• How? The transfer of momentum allows the weights
  on opposite sides to make the pendulum back and
  forth.

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Atom- the basic unit of matter

• 3 particles
• Protons charge
• Neutrons no charge
• Electrons charge
• If an atom has more protons than electrons, the
  atom is positively charged. If an atom has more
  electrons than protons, the atom is negatively
  charged.

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Static and Current Electricity
Electricity is a form of energy used around the
world. Static electricity is the build-up of
electrons. (Lightning) Current electricity is the
flowing of electrons. (Wall Outlets)
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Sources of Electricity

• Natural
• Lightning
• Electric Eels
• Static

• Human-Made
• Batteries
• Generators
• Solar Cells
• Wall Outlets

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Circuits

• Circuit- a complete path through which
  electricity can flow.
• Closed circuits allow electricity to flow.
• Open circuits do not allow electricity to flow.
• Conductors-materials with loosely bound electrons
  that allow electricity to flow through them.
  (metals, iron, silver, aluminum)
• Insulators-materials with tightly bound electrons
  that do not allow electricity to flow through
  them. (wood, plastic, glass)

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Series and Parallel Circuits

• Series Circuits
• One path
• If one light goes out, all go out
• Simple
• The more bulbs, the dimmer they get

• Parallel Circuits
• Several paths
• If one light goes out, others stay lit
• Complex
• More bulbs do not affect the brightness, because
  they have their own paths

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Switches and Short Circuits

• Switches turn electricity off and on by opening
  or closing a circuit.
• Short Circuits occur when electricity can bypass
  a component in a circuit.
• Electricity takes the path of least resistance
• Short Circuits are dangerous
• The energy from the battery is drained quickly

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Resistance

• The opposition to the flow of electricity
• The greater the resistance, the dimmer the bulb
• Percent Error- difference between the code and
  measured value of a resistor divided by the code
  multiplied by 100.
• Difference/code x 100

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Electrical Safety

• Lightning Rods- rods on tall buildings that send
  lightning to a grounding wire.
• Circuit Breaker- device that shuts off
  electricity when there is too much flowing
  through a circuit.
• Fuse- a thin metal strip of wire that melts when
  there is too much electricity going through a
  circuit.

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Voltage

• The push behind the current in a circuit.
• Voltage Drop is the voltage used up by a
  component.
• The sum of the voltage drops in a circuit equals
  the voltage from the source (First Great Truth).
• The greater the resistance, the more voltage
  needed to push the current through (Second Great
  Truth).

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Mystery Components

• Diode-semiconductor that only lets electricity
  flow in one direction (Radio Stations)
• LED (Light Emitting Diode)- a diode that lights
  up (Game Shows)
• Capacitor-stores electricity and lets out little
  bursts of light (camera flash)
• Motor-changes electrical energy(electricity) into
  mechanical(motion) energy (electric fan)

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Transformation of Energy

• Motor- changes electrical energy into mechanical
  energy
• Generator- changes mechanical energy into
  electrical energy
• Fossil Fuels- change solar energy to heat energy
  to mechanical energy to electrical energy
• Battery- changes chemical energy to electrical
  energy

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Fossil Fuels

• Definition plant or animal remains found in
  rocks underground
• Examples coal, oil, and natural gas
• How Drilling removes these fuels from
  underground and they are burned to create steam
  to turn the turbine which then activates the
  generator.
• Pros-effective, inexpensive
• Cons-pollution, oil spills, nonrenewable

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A Few Alternative Energy Sources

• Hydroelectric Power (Water)
• Wind Power
• Solar Power

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Hydroelectric Power

• Dams are built to hold back running water. Small
  tunnels let water flow to turn the turbine which
  activates the generator.
• Pros No Pollution, Once dam is built,
  inexpensive, effective, renewable
• Cons Building a dam is expensive, floods,
  animals in the water could get stuck in the
  turbine

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Wind Power

• Wind turns propellers that act like turbines to
  activate the generator
• Pros-wind is free, no Pollution
• Cons-inconsistent, requires a great deal of land
  near coastal areas, land is expensive, birds may
  get caught in propellers, noisy

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Solar Power

• Energy from the sun reflects off of mirrors,
  boils water, and the heat can create steam which
  turns the turbine, activating the generator.
• OR
• Solar Cells can convert light directly into
  electricity
• Pros- The sun is free, renewable, and causes no
  pollution
• Cons-Does not work at night, very expensive to
  build solar panels, needs to be in sunny locations

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Electromagnets

• Strong magnets that can be turned on and off.
• Includes
• Voltage Source
• Ferromagnetic Core
• Solenoid (coil of wire)
• To increase its strength, increase
• 1. Voltage from source
• 2. Nature of Ferromagnetic Material
• 3. Number of coils on solenoid and make them
  close together