February 26, 2009DRILL

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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 IDEABIG IDEA

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UNIT 3 – Engineering Design

a. Getting familiar with the Big Idea

b. The Design Process

c. Core Technologies

d. Mechanical Technology

e. Electrical Technologyf. Reverse Technology

g. Fluid Technology

h. Thermal Technology

i. Optical Technology

j. Materials Technology

SUB-UNITSSUB-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.

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• 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:Imagine:

Electrical Technology

Core Technologies

Mechanical

Structural Electrical

Electronic Thermal

Fluid Optical

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• 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 TechnologyElectronic Technology

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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 TechnologyElectrical Technology

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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 sun’s energy into electricity

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• 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.

Electrical Technology

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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

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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.

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CIRCUITS

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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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• 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

GoldWoodPlastic

SilverAluminum

Air

Copper

Free Electrons

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INSULATOR

BOUND ELECTRONS

CONDUCTOR

FREE ELECTRONS

Cotton

WoodPlastic

Air

Copper

AluminumGold

Silver

HOMEWORKHOMEWORK

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.