ELECTROMAGNETISM

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ELECTROMAGNETISM
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Bell Work

• Welcome back, I hope you had a great break!
• (Write each statement then decide if it is true
  or false, if false correct)
• The basic particles of an atom are protons,
  neutrons, and nuclei.
• Particles that make up an atom have no charge.
• Electrons are negatively charged.

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Electricity 1.1 Vocab

• Electric charge a property that allows an
  object to exert an electric force on another
  object without touching it.

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1.1 Vocab Cont.

• Electric field the space around a particle
  through which an electric charge can exert force

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1.1 Vocab Cont.

• Static charge a buildup of electric charge in
  an object caused by the presence of many
  particles with the same charge

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1.1 Vocab Cont.

• Induction the buildup of a charge without
  direct contact

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Bell Work

• Draw a picture and explain each answer.
• 1. How do two positive particles interact?
• 2. How do two negative particles interact?
• 3. How do a positive and a negative particle
  interact?

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Bell Work

• Please answer the following questions using
  complete sentences.
• A sock and a shirt from the dryer stick together.
  What does this tell you about the charges on the
  sock and shirt?
• 2. You walk over a rug and get a shock from a
  doorknob. What do the materials of the rug and
  the shoes have to do with the type of charge your
  body had?

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AssignmentRead pg 18- 25 then

• Choose one of the following to complete
• Make a PowerPoint for the vocab words on page 18.
  Each word should have 2 slides. First slide
  word, definition, and a sentence in your own
  words. Second slide word and a picture.
• Make a 4 square chart ?
• For each of the vocab
• words on page 18.

Word Definition
Use in a sentence in your own words Draw a picture.
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1.2 Vocab

• Electric potential the amount of electric
  potential energy per unit charge at a certain
  position in an electric field.
• Volt equal to one joule of energy per coulomb
  of charge

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• Conductor a material that allows an electric
  charge to pass through it easily
• Insulator a material that does not easily allow
  a charge to pass through it.

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• Resistance the property of a material that
  determines how easily a charge can move through
  it
• Ohms the unit for measuring electrical
  resistance

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• Grounding providing a harmless, low-resistance
  path (a ground) for electricity to follow

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Bell Work 5/12/11

• Draw a picture and explain what happens when
  there is lightning. (hint look at pg 25)

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Bell Work 5/11/11

• Please read page 17 about Electric Eels. Write 3
  sentences about what you learned and answer 1.
  Please use complete sentences.

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Bell Work 5/12/11

• Make a chart with at least 5 conductors and 5
  insulators in it.

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Bell Work 5/13/11

1. What is electric potential?
2. What 3 factors affect how much electrical
   resistance an object has?
3. How can a lightning rod protect a building from
   fire?

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Bell Work 5/16/11

1. Why do lightning rods work better if they are
   placed high up, closer to the lightning charge?
2. Could the same material be used as both a
   conductor and an insulator? Explain your answer.

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Bell Work 5/17/11

1. Draw a picture of a wire with low resistance.
2. Draw a picture of a wire with high resistance.
3. What might wire made with low resistance be used
   in?
4. What might wire with high electrical resistance
   be used in?

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Bell Work

1. How much resistance does a superconducting
   material have? (pg 24)
2. What is a ground cable? (pg 25)

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1.3 Notes

• Electric Current the flow of charge (,-)
  through a material.
• Electric currents produce magnetic fields ---
  spinning/moving electrons.

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• Circuit complete path through which electric
  charges can flow.
• 1. circuit has a source of electrical energy.
• 2. circuits have devices that are run by
  electrical energy.
• 3. electric circuits are connected by conducing
  wires and a switch.

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• Ampere the standard unit of measure for current
• Ohms law shows relationship between current,
  voltage, and resistance
• Current Voltage I V
• Resistance R

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• Electric cell produces electric current using
  the chemical or physical properties of different
  materials

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• Primary cell produce electric current through
  chemical reactions until the chemicals are all
  used up
• Storage cell produce electric current through
  chemical reactions that can be reversed in the
  battery

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Bell Work 5/19/11

• Make a Venn diagram comparing and contrasting
  electric current and static discharge.

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Bell Work 5/24/10

• Good morning. Please get out your study guide and
  begin reviewing for the final.

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Bell Work

1. Where do solar cells get their energy?
2. What kind of battery can be charged by reversing
   chemical reactions?
3. What does an ohmmeter measure?
4. In which direction do electrons flow when a
   storage cell is being charged?

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Bell Work 5/25/11

1. An electrical pathway has a voltage of 240 volts
   and a current of 10 amperes. What is the
   resistance?
2. A 240-volt air conditioner has a resistance of 8
   ohms. What is the current?
3. An electrical pathway has a current of 1.2
   amperes and resistance of 40 ohms. What is the
   voltage?

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Bell Work

• Write a paragraph about your favorite part of
  science class this year and your least favorite
  part of science class this year
• - Then get out your study guide and review

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• Magnetism The attraction of a magnet for
  another object.
• Magnetic pole end of a magnet, a pole is the
  area of a magnet where the magnetic effect is
  strongest. Pg 18
• alike poles repel and opposites poles
  attract each other.
• Magnetic Fields - the region of magnetic force
  around a magnet.

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• Inside a Magnet
• Atom smallest particle of an element that has
  the properties of that element.
• Element Is on of about 100 basic materials that
  make up all matter.
• Nucleus Center of an atom that contains the
  PROTON and the NEUTRON.

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• Proton the positive charged particle of an
  atom.
• Neutron Contain mass only (NO CHARGE).
• Electron Very small particle Found circling the
  nucleus with a negative charge.

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• The spinning of the electrons in an atom causes
  an magnetic field.
• Magnetic domain when a large portion of the
  atoms in a material are lined up in the same way.
• In a magnetized material all or most of the
  domains are arranged in the same direction.
• Iron is a substance that will undergo magnetism
  because the domains can be aligned to have a
  strong magnet.

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• Temporary magnets when domains are alligned for
  a short period of time. Like placing a magnet on
  a group of paper clips

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• Permanent magnet A magnet made of a material
  that keeps its magnetism. The more iron in the
  magnet the better (stronger) the magnet.
• Earth as a Magnet
• Although not completely understood the popular
  theory is --- the molten iron and nickel core is
  spinning causing the generation of a magnetic
  field around Earth.
• Earth has both a North and South magnet pole,
  just as a bar magnet does.

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• Magnetic Declination the angle between
  geographic north (true north) and the north to
  which a compass needle points.
• Magnetic north is 1250 km (776 miles) from
  geographic north.
• Magnetosphere -

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• The Earth will actually make iron object
  magnetized over a long period of time, if the
  object doesnt move.
• The rock that forms from lava will have a
  magnetic domain facing the poles of the Earth.
  Over 800,000 year the magnet poles of the Earth
  will swap. Don't know why, but da do!!!

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• Electric Current the flow of charge (,-)
  through a material.
• Electric currents produce magnetic fields ---
  spinning/moving electrons.
• Circuit complete path through which electric
  charges can flow.
• 1. circuit has a source of electrical energy.
• 2. circuits have devices that are run by
  electrical energy.
• 3. electric circuits are connected by conducing
  wires and a switch.

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Flow of electrons, energy source
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• Resistance the opposition to the movement of
  charges flowing through a material.
• Superconductors materials that have no
  resistance to electrical flow. NO LOSS OF ENERGY
  occurs in a superconductor.
• Solenoid a current carrying coil of wire with
  many loops.
• Electromagnet a solenoid with a ferromagnetic
  core. Can be turned off and on.

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• B

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• Resistor A resistor uses electrical energy or
  resists the flow of charge in an electrical
  circuit.
• Light bulb, any electrical appliance.

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• Electricity
• The unit of current is the ampere or amp.
• It tells the amount of charge flowing past a
  point at any given second.
• ALL MAGNETISM IS CAUSED BY MOVEMENT OF CHARGES.
• http//www.pbs.org/wgbh/amex/edison/sfeature/acdc.
  html

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• Conductors Electrons are loosely bound to the
  atom and electrical currents move freely through
  the wire.
• Copper, aluminum, silver and iron.
• Insulators Electrons are bound tightly to atom
  and do not flow easily.
• Rubber, glass, plastic, sand, wood.

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• Static Electricity Charges build up, but do not
  flow.
• Caused by
• Friction-transfer of electrons from one object to
  another by rubbing.
• Ex clothes in a dryer

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• Conduction the transfer of electrons by direct
  contact.
• Ex touching a car door or someone and getting
  shocked!
• Induction the movement of electrons to one part
  of an object caused by the electric field of
  another object.
• Voltage The force that pushes the electrical
  charge through the wire.

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• Series Circuit Only one path for the current to
  take.
• Pro Simple and cheap to make
• Cons 1. If one light goes out, they all do
• Lights become dimmer as you add more bulbs (less
  current and more resistance!)

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• Parallel Circuit Several paths for the current
  to take.
• Pro Individual bulbs can be turned on and off
  without affecting each other. Ex
• Household circuits

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• A scientist is experimenting with bacteria that
  are one micron in diameter and that reproduce by
  dividing every minute into two bacteria. At
  1200 PM, she puts a single organism in a
  container. At precisely 100 PM, the container is
  full.
• At what time was the container half full?
• 2.There are twelve identical-looking balls, but
  one is either heavier or lighter than the other
  eleven. How can you determine which is the odd
  ball and find out whether this ball is heavier or
  lighter than the others using only three
  weighings with a balance?

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Bell Work

1. What is going to be the most difficult part about
   building your box?
2. What is going to be the easiest part about
   building your box?

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Bell Work

• If you could make 3 changes to your box what
  would they be? Please write a paragraph to
  answer the question.