Technological Impacts

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February 2011 DRILL

• Write the question and circle the answer you
  think is
• correct . Next, write why?

What kind of power source do you think provides
the proper current for this shaver to work?
It uses direct current because it is powered
by a battery. If it used alternating current
you would be able to plug it into a wall outlet.
We will find out more about AC and DC current in
this unit.
A) AC (Alternating Current) B) DC (Direct
Current)
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UNIT 3 Engineering Design

1. Getting familiar with the Big Idea
2. The Design Process
3. Core Technologies
4. Mechanical Technology
5. Electrical Technology
6. Reverse Technology
7. Fluid Technology
8. Thermal Technology
9. Optical Technology
10. Materials Technology

SUB-UNITS
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Electrical Technology

• PURPOSE OF SUB-UNIT

• To familiarize students with the functioning and
  applications of electrical technology systems by
  having you analyze the functioning of electrical
  systems in terms of their
• common components,
• basic system design,
• safety considerations, and
• simple controls.

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What is this technology system?

• A technology system is a group of resources
  (subsystems) working together to solve problems
  and extend human capabilities.
• What subsystems make up this system?
• Identify the problem that the technology system
  solves.
• Speculate on how the device assists people in
  solving a problem or extending human capability.

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Electronic Technology
Definition The technology of using small
amounts of electricity for controlling,
detecting, collecting, storing, retrieving and
processing information.
Applications Thermostat, metal detector,video
recorder, computer,calculator,
telephone,television, radio, pace maker, digital
watch.
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Electrical Technology
Definition The technology of producing,
storing, controlling, transmitting and getting
work from electrical energy.
Applications Power plant generator,
flashlight, electric motor in a can opener,
doorbell, electric heater, hair dryer.
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Electrical Technology

• Electricity completely surrounds us.
• For most of us, modern life would be impossible
  without it.
• Examples
• Electrical outlets along walls in your
  house/school
• Portable devices (cell phones, ipods,
  calculators) powered by batteries
• Bolts of electricity (lightning) during
  thunderstorms
• Static electricity on dry winter days
• Solar cells converting the suns energy into
  electricity

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Electrical Technology

• Electricity can be used in a thousand different
  ways. For example
• Electric motors turn electricity into motion.
• Light bulbs, fluorescent lamps and LEDs turn
  electricity into light.
• Computers turn electricity into information.
• Telephones turn electricity into communication.
• TVs turn electricity into moving pictures.
• Speakers turn electricity into sound waves.
• Stun guns turn electricity into pain.
• Toasters, hair dryers and space heaters turn
  electricity into heat.
• Radios turn electricity into electromagnetic
  waves that can travel millions of miles.
• X-ray machines turn electricity into X-rays.

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ELECTRONS

• Electricity begins with Electrons.

• ATOMS
• Electron cloud surrounds an atoms nucleus
• Nucleus is made of
• Electrons negative charge
• Protons positive charge
• Neutrons zero charge (neutral)

Protons and Neutrons
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Pity the poor neutronhe thought he was a
protonbut he wasnt positive.
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• Electric Charge and Electrical Forces
• Electrons have a negative electrical charge.
• Protons have a positive electrical charge.
• These charges interact to create an electrical
  force.
• Like charges produce repulsive forces so they
  repel each other (e.g. electron and electron or
  proton and proton repel each other).
• Unlike charges produce attractive forces so
  they attract each other (e.g. electron and proton
  attract each other).

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All of us agree the importance of electricity in
our daily lives. But
what is electricity?
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• Electricity is a basic feature of all matter, of
  everything in the universe. Electrical force
  holds atoms and molecules together. Electricity
  determines the structure of every object that
  exists. Together with magnetism, it causes a
  force called electromagnetism, a fundamental
  force of the universe.
•  
• Electricity or electrical signals are essential
  to many biological processes. In our bodies,
  electrical signals are carried through the
  nervous system, moving information to and from
  the brain. Electrical signals communicate to our
  brain what the eyes see, what the ears hear, and
  what the fingers feel. Electrical signals from
  our brain causes our muscle movements. Electrical
  signals cause each heartbeat.
•  
• One of the most important forms of electricity is
  in electrical current. During the industrial
  revolution of the 1800s, people began to find
  ways to use electricity to do work. Today
  electricity is used throughout our homes, at
  work, in communication, in transportation, and in
  medicine and science. Electrically powered
  devices are prevalent. Relatively cheap
  electricity has made electrical appliances,
  machines, and other devices possible.
•  

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What is static electricity? When two objects rub
against each other electrons transfer and build
up on an object causing it to have a different
charge from its surroundings. Like the shoes
rubbing against the carpet. Electrons are
transferred from the carpet to the shoes.
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As electrons collect on an object, it becomes
negatively charged. As electrons leave an object
it attains a positive charges. Charges interact
with each other
Often when you remove clothes from the clothes
dryer, they seem to stick together. This is
because some of the clothes have gained electrons
by rubbing against other clothes. The clothes
losing electrons become positive. The negative
clothes are attracted to the positive clothes.
Have you ever rubbed a balloon on your hair and
stuck it on a wall? How do you think this works?
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What causes you to be shocked when you rub your
feet across carpet?
An electrical discharge is the passing of an
electric current through the air from a
negatively charged object to a positively charge
object. This is what causes lightning!
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Arbitrary numbers of protons () and electrons
(-) on a comb and in hair (A) before and (B)
after combing. Combing transfers electrons from
the hair to the comb by friction, resulting in a
negative charge on the comb and a positive charge
on the hair.
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• The charge on an ion is called an electrostatic
  charge.
• An object becomes electrostatically charged by
• Friction,which transfers electrons between two
  objects in contact,
• Contact with a charged body which results in the
  transfer of electrons,
• Induction which produces a charge redistribution
  of electrons in a material.

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Charging by induction The comb has become
charged by friction, acquiring an excess of
electrons. The paper (A) normally has a random
distribution of () and (-) charges. (B) When
the charged comb is held close to the paper,
there is a reorientation of charges because of
the repulsion of the charges. This leaves a net
positive charge on the side close to the comb,
and since unlike charges attract, the paper is
attracted to the comb.
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Lightning (1)
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HOMEWORK

• Identify 5 electrical technologies not mentioned
  in class today
• (Remember, an electrical technology produces,
  stores, controls, transmits or gets work from
  electrical energy)
• Identify the problem that the technology system
  solves
• List the technological subsystems that are used
  in the technology
• Identify the technology that preceded it (i.e.
  what was used before the technology was
  invented?)
• EXTRA CREDIT Air is an insulator. Come to class
  tomorrow and explain how lightning happens.

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February 2011DRILL

1. What are the three methods an object can become
   electrostatic?
2. What are three components of an atom?
3. What are the charges of each component?
4. Which component is the basis for electricity?

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February 9, 2011DRILL

1. What are the three methods an object can become
   electrostatic? Friction, Contact, Induction
2. What are three components of an atom? Electrons,
   Protons, and Neutrons
3. What are the charges of each component?
   Electrons-negative, Protons-positive, and
   Neutrons-neutral
4. Which component is the basis for electricity?
   Electrons

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Yesterday's HOMEWORK

• Identify 5 electrical technologies not mentioned
  in class today
• (Remember, an electrical technology produces,
  stores, controls, transmits or gets work from
  electrical energy)
• Identify the problem that the technology system
  solves
• List the technological subsystems that are used
  in the technology
• Identify the technology that preceded it (i.e.
  what was used before the technology was
  invented?)
• EXTRA CREDIT Air is an insulator. Come to class
  tomorrow and explain how lightning happens.

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CIRCUITS

• The paths that electrons travel are called
  circuits.
• Circuits must consist of three things

ELECTRONS move from negative ( - ) terminal
to positive ( ) terminal

• Power Source with positive and negative
  terminals.
• Conductor the path the electrons travel along.
• Load this is what the electricity powers (e.g.
  motor, light bulb)

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What is the difference between static electricity
and current electricity?
Static electricity is stationary or collects on
the surface of an object, whereas current
electricity is flowing very rapidly through a
conductor. The flow of electricity in current
electricity has electrical pressure or voltage.
Electric charges flow from an area of high
voltage to an area of low voltage.
Water pressure and voltage behave in similar ways.
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CIRCUITS

• Moving electrons have energy.
• Electrons moving through a wire (conductor) in a
  circuit have energy.
• As the electrons move from one point to another,
  they can do work.
• Electrical Technology harnesses the energy of
  electrons to do work.

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A simple electric circuit has a voltage source
(such as a generator or battery) that maintains
the electrical potential, some device (such as a
lamp or motor ) where work is done by the
potential, and continuous pathways for the
current to follow.
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• The Electric CircuitAn electrical circuit
  contains some device that acts as a source of
  energy as it gives charges a higher potential
  against an electrical field.
• The charges do work as they flow through the
  circuit to a lower potential.
• The charges flow through connecting wires to make
  a continuous path.
• A switch is a means of interrupting or completing
  the circuit.
• The source of the electrical potential is the
  voltage source.

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(No Transcript)
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The pressure of the water flowing through the
pipes on the last slide compare to the voltage
(electric potential) flowing through the wires of
the circuit. The unit used to measure voltage is
volts (V). The flow of charges in a circuit is
called current. Current (I) is measured in
Amperes (A).
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CONDUCTORS

• Conduct from Latin for leading, guiding.
• A conductor is any material that allows electrons
  to easily flow.
• Remember the atom
• Conductors electrons are not tightly bound to
  the atom.
• Conductors have free electrons.
• Which material has free electrons, Wood or Metal?
• Metals conduct electricity easily.

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(A) A metal conductor without a current has
immovable positive ions surrounded by a swarm of
randomly moving electrons. (B) An electric
field causes the electrons to shift positions,
creating a separation charge as the electrons
move with a zigzag motion from collisions with
stationary positive ions and other electrons.
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The four factors that influence the resistance of
an electrical conductor are the length of the
conductor, the cross-sectional area of the
conductor, the material the conductor is made of,
and the temperature of the conductor.
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INSULATORS

• Insulate from Latin for separate, divided.
• An insulator is any material that impedes the
  flow of electrons.
• Remember the atom
• Insulators electrons are tightly bound to the
  atom.
• Because the electrons dont move, insulators
  cannot conduct electricity very well, if at all.
• Which material has bound electrons, Wood or
  Metal?
• Wood does not have free electrons.

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Cotton
Bound Electrons
Gold
Wood
Plastic
Silver
Aluminum
Air
Copper
Free-electrons
INSULATOR Cotton Wood Plastic Air BOUND
ELECTRONS
CONDUCTOR Copper Gold Silver Aluminum FREE
ELECTRONS
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HOMEWORK

1. List 5 electrical devices you absolutely need and
   why.
2. List 5 electrical devices you do not need.