February 26, 2009 DRILL U3e-L1 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. 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? A) AC (Alternating Current) B) DC (Direct Current)

UNIT 3 – Engineering Design Engineering, the systematic application of mathematical, scientific, and technical principles, produces tangible end products that meet our needs and desires. BIG IDEA U3e-L1

UNIT 3 – Engineering Design a.Getting familiar with the Big Idea b.The Design Process c.Core Technologies d.Mechanical Technology e.Electrical Technology f.Reverse Technology g.Fluid Technology h.Thermal Technology i.Optical Technology j.Materials Technology SUB-UNITS

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. U3e-L1

Electrical Technology What is technology? The application of knowledge, tools, and skills to solve problems and extend human capabilities. What is a technology system? A Technology System is a group of subsystems working together to solve problems and extend human capabilities. U3e-L1

There are several engineering resources (core technologies) that are the “building blocks” of all technology systems. We could store the core technologies on shelves We can go to those shelves and use technologies according to our needs in problem solving. Imagine: Electrical Technology Core Technologies Mechanical StructuralElectrical ElectronicThermal FluidOptical Bio-TechMaterial U3e-L1

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. What is this technology system?

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. Electronic Technology U3e-L1

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. Electrical Technology U3e-L1

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 sun’s energy into electricity

U3e-L1 Electricity can be used in a thousand different ways. For example: –Electric motors turn electricity into motion.Electric motors –Light bulbs, fluorescent lamps and LEDs turn electricity into light.Light bulbsfluorescent lampsLEDslight –Computers turn electricity into information.Computers –Telephones turn electricity into communication.Telephones –TVs turn electricity into moving pictures.TVs –Speakers turn electricity into sound waves.Speakers –Stun guns turn electricity into pain.Stun guns –Toasters, hair dryers and space heaters turn electricity into heat.Toastershair dryers –Radios turn electricity into electromagnetic waves that can travel millions of miles.Radios –X-ray machines turn electricity into X-rays.X-ray machines Electrical Technology

U3e-L1 ELECTRONS Electricity begins with Electrons. ATOMS Electron cloud surrounds an atom’s nucleus Nucleus is made of Electrons – negative charge Protons – positive charge Neutrons – zero charge (neutral) Protons and Neutrons

U3e-L1 LOAD 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) CIRCUITS The paths that electrons travel are called circuits. Circuits must consist of three things: ELECTRONS move from negative ( - ) terminal to positive ( + ) terminal

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. U3e-L1 CIRCUITS

U3e-L1 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.

U3e-L1 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 don’t move, insulators cannot conduct electricity very well, if at all. Which material has bound electrons, Wood or Metal? Wood does not have free electrons. INSULATORS

Cotton Bound Electrons Gold Wood Plastic Silver Aluminum Air Copper Free Electrons U3e-L1 INSULATOR BOUND ELECTRONS CONDUCTOR FREE ELECTRONS Cotton Wood Plastic Air Copper Aluminum Gold Silver

HOMEWORK 1.Identify 5 electrical technologies not mentioned in class today (Remember, an electrical technology produces, stores, controls, transmits or gets work from electrical energy) 2.Identify the problem that the technology system solves 3.List the technological subsystems that are used in the technology 4.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.