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8 Electrical Engineering Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Objectives Define electrical engineering.

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Presentation on theme: "8 Electrical Engineering Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Objectives Define electrical engineering."— Presentation transcript:

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2 8 Electrical Engineering

3 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Objectives Define electrical engineering. Explain the secondary and college level education requirements for employment in the electrical engineering profession. Explain how electrons move on an atomic level. Describe the characteristics of voltage, current, resistance, and power. Explain Ohms law and use it to solve for values in a circuit. Identify the operation and application of common electronic components such as resistors, switches, capacitors, diodes, and transistors.

4 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. About Electrical Engineering Engineering field that deals with electricity and electronics Electrical engineers design, build, and test electrical devices and facilities About 21% of all engineers are electrical engineers

5 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Educational Requirements Bachelors degree in electrical engineering Higher degrees often required for higher level positions Coursework in electricity, electronics, chemistry, biology, physics, and higher level math and statistics Associates degree required for electrical technicians

6 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Professional Organization Institute of Electrical and Electronics Engineers (IEEE) –Broadest professional society for electrical engineers –Over 375,000 members –Dedicated to advancing technological innovation and excellence through publications, conferences, standards, and activities

7 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Electricity on the Atomic Level Electrons, protons, neutrons Valence shell Electron movement Electrically charged atoms are called ions Goodheart-Willcox Publisher

8 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Static Electricity Excess of charge on objects surface Many industrial applications Electrostatic precipitator –Used to remove particles from air –Charged particles stick to collection plates with opposite charge

9 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Electricity Through Conductors Negative to positive flow using electron flow theory Move slowly, but the effective speed is about the speed of light Goodheart-Willcox Publisher

10 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Sources of Electricity Some form of energy is converted into electrical energy Three sources of electricity –Magnetism –Chemical action –Solar cells

11 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Law of Conservation of Energy States that energy cannot be created or destroyed Energy can only be converted from one form to another

12 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Magnetism Generators produce electricity by changing mechanical energy to electrical energy Voltage induced in wire when magnet passes Current induced in conductor of generator Steam, water, or wind turns turbines, creating motion that spins generators

13 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Chemical Action Cells use chemical action to create electricity Batteries connect multiple cells Electrodes of different materials has voltage created between them Two types of cells –Primary cells –Secondary cells

14 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Solar Cells Use light to create electricity Semiconductors with positive and negative layers absorb some light energy Energy causes electrons to flow in form of current Cells can power devices and houses

15 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Characteristics and Measurements Generated electricity has certain characteristics that can be used in different ways Engineers must understand characteristics and how to measure them –Voltage –Current –Resistance

16 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Voltage Amount of pressure causing flow of electrons Expressed as electromotive force (EMF) Also called potential difference because it describes difference in charge from one place to another Measured in volts

17 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Current Measure of electrons per unit time Also called amperage Measured in amperes (amps) One ampere is one coulomb of charge passing a point in one second One coulomb equals 6.24 10 18 electrons

18 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Polarity Refers to positive or negative condition at power supply terminal Direct current (dc) occurs when polarity is constant and current flows in only one direction Alternating current (ac) occurs when polarity changes back and forth from positive to negative, causing current to change direction

19 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Resistance Opposition to current flow Measured in ohms (Ω) Current flow limited and voltage divided by resistors Resistant materials are insulators Inversely proportional to current

20 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Power The rate at which work is done or amount of work done based on period of time Electrical power is product of voltage and current Measured in watts One watt is one volt moving one coulomb of electricity in one second

21 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Laws Ohms law –Discovered by George Ohm –Describes relationship between voltage, current, and resistance Watts law –Power equals effort multiplied by rate –Used to find any one of three values when two are known

22 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Basic Circuits Series circuits Parallel circuits Series-parallel combination circuits

23 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Series Circuits One path for current flow Total voltage equals sum of drops across all loads Total resistance equals sum of resistance of each load Current remains constant throughout Goodheart-Willcox Publisher

24 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Parallel Circuits Multiple paths for current flow Total voltage is equal to the voltage across each branch Total current is equal to the sum of branch currents

25 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Series-Parallel Combination Circuits Circuits with characteristics of both series and parallel Parallel parts must be broken down and studied as if they were series elements Goodheart-Willcox Publisher

26 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Schematics Schematic symbols are used to show components in circuit drawings Schematic diagrams use symbols and lines to connect components Often used in building and troubleshooting circuitry Design

27 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Circuit Components Each component must be understood Understanding is necessary for design and troubleshooting Three main types of components –Conductors –Control components –Output components

28 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Conductors Materials have low resistance –Copper –Aluminum –Silver –Gold Different configurations American Wire Gauge (AWG) system determines size

29 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Control Components Insulators Resistors Variable resistors Switches Diodes Zener diodes Transistors Capacitors Integrated circuits (ICs) Semiconductors Sensors

30 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Insulators Very high resistance Do not conduct electricity under normal circumstances Keep electricity confined to desired path –Plastic –Rubber –Dry wood/paper –Glass/ceramics –Mica

31 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Resistors Limit current flow and divide voltage Most are made from carbon Color coding system marks the value of resistors Goodheart-Willcox Publisher

32 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Variable Resistors Vary amount of resistance in dimmer switches and fan speed switches Two terminals and wiper, which changes amount of resistive material between terminals Represented by arrow symbol

33 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Switches Open and close circuits Change direction of flow Characterized by type of switch, number of poles, and number of throws –SPST switch can turn current on or off to circuit –SPDT switch can direct current in one direction or other

34 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Diodes Standard diodes allow current flow in only one direction Have two electrodes –Anode is made of positive semiconductor material –Cathode is made of negative semiconductor material Current flows in forward bias condition only Can be used as rectifiers

35 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Zener Diodes Zener diodes are wired in reverse bias Block current until voltage reaches certain level Keep voltage at constant level Used as voltage regulators

36 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Transistors Used as solid state switches and amplifiers Perform switching function without moving parts Bipolar transistors have three junction points –Emitter –Base –Collector Can also be used as amplifiers

37 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. NPN and PNP Transistors Goodheart-Willcox Publisher

38 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Capacitors Store and discharge electricity very quickly Smooth out variations in voltage Two conductive plates separated by thin insulator called dielectric Ceramic disc and electrolytic Can maintain charge long after power source is removed

39 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Integrated Circuits (ICs) Multiple electrical circuits etched into thin layer of silicon Dot or notch on outside of chip is used for orientation Can be sensitive to static Common example is 555 timer

40 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Semiconductors Materials with conductive capabilities between that of conductors and insulators Silicon is most common type Used in different components –Transistors –Diodes –Solar panels –Integrated circuits

41 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Sensors Create an electrical signal based on environmental conditions Signal changes as environmental conditions change Common example is electronic thermostats

42 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Output Components Incandescent lamps Gas discharge lamps Fluorescent lamps Compact fluorescent lamps (CFLs) Light-emitting diode (LED) lamps Motors

43 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Incandescent Lamps Creates light when current flow causes tungsten filament to become so hot it glows All air inside glass globe is evaluated and sometimes replaced with argon Traditional incandescent bulbs are being phased out

44 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Gas Discharge Lamps Ionized glass and free electrons cause gas to glow and create light Neon lamps are example, but other gases may be used Resistor must be placed in series with light to limit current flow

45 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Fluorescent Lamps Long glass tube coated on inside with phosphorous and filled with inert gas and mercury Electrical current passed through mercury causes ultraviolet light, which causes phosphorous to glow Use much less electricity than incandescent lamps

46 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Compact Fluorescent Lamps (CFLs) Work on same principle as fluorescent lamps but fit into standard light socket Use about 75% less energy than incandescent lamps Last up to ten time longer than incandescent lamps

47 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Light-Emitting Diode (LED) Lamps Create light by wiring semiconductor material in forward biased position Forward biased direct current passes through semiconductor in LED casing, and light is emitted Low cost, efficient, and long lasting

48 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Motors Convert electrical energy into mechanical energy Electromagnet spins until its north pole lines up with south pole of permanent magnet Polarity of electromagnet reverses, causing it to keep rotating

49 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Component Platforms Circuit boards Solderless breadboards Electronic circuit simulation

50 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Circuit Boards Commonly known as printed circuit boards (PCBs) Copper track laid on fiberglass Electronic components are soldered to copper track

51 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Solderless Breadboards Ideal for experimentation Can be used to test circuits before they are constructed Components and leads can easily be added and removed because no soldering is required

52 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Electronic Circuit Simulation Can be used to simulate performance of circuitry without having to build circuit Components are laid out on-screen Software shows how circuits would work Problems can be identified early on

53 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Meters Ammeters Voltmeters Ohmmeters Volt-ohm-milliammeters (VOM) Continuity tester Oscilloscope Tools

54 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Troubleshooting First step may be to test voltage Continuity tester or ohmmeter may be used to ensure continuity exists Test to see if diode conducts in forward bias and not reverse LEDs can be tested by applying voltage directly

55 Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., Inc. Electrical Engineering in Action Hybrid cars –Combine internal combustion engine and batteries –Regenerative braking –Increased fuel mileage Goodheart-Willcox Publisher


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