2. Electrical Engineering8
Electrical Engineering

3. 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 Ohm’s 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. 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. Educational Requirements
Bachelor’s 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
Associate’s degree required for electrical technicians

6. 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. Electricity on the Atomic Level
Electrons, protons, neutrons
Valence shell
Electron movement
Electrically charged atoms are called ions
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8. Static Electricity Excess of charge on object’s surface
Many industrial applications
Electrostatic precipitator
Used to remove particles from air
Charged particles stick to collection plates with opposite charge

9. Electricity Through Conductors
Negative to positive flow using electron flow theory
Move slowly, but the effective speed is about the speed of light
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10. Sources of Electricity
Some form of energy is converted into electrical energy
Three sources of electricity
Magnetism
Chemical action
Solar cells

11. Law of Conservation of Energy
States that energy cannot be created or destroyed
Energy can only be converted from one form to another

12. 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. 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. 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. 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. 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. 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  1018 electrons

18. 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. 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. 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. Laws Ohm’s law Watt’s law Discovered by George Ohm
Describes relationship between voltage, current, and resistance
Watt’s law
Power equals effort multiplied by rate
Used to find any one of three values when two are known

22. Basic Circuits Series circuits Parallel circuits
Series-parallel combination circuits

23. 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
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24. 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. 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
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26. Design
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

27. 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. Conductors Materials have low resistance Different configurations
Copper
Aluminum
Silver
Gold
Different configurations
American Wire Gauge (AWG) system determines size

29. Control Components Insulators Transistors Resistors Capacitors
Variable resistors
Switches
Diodes
Zener diodes
Transistors
Capacitors
Integrated circuits (ICs)
Semiconductors
Sensors

30. 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. Resistors Limit current flow and divide voltage
Most are made from carbon
Color coding system marks the value of resistors
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32. 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. 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. 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. 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. 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. NPN and PNP Transistors
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38. 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. 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. 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. Sensors Create an electrical signal based on environmental conditions
Signal changes as environmental conditions change
Common example is electronic thermostats

42. Output Components Incandescent lamps Gas discharge lamps
Fluorescent lamps
Compact fluorescent lamps (CFLs)
Light-emitting diode (LED) lamps
Motors

43. 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. 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. 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. 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. 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. 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. Component Platforms Circuit boards Solderless breadboards
Electronic circuit simulation

50. Circuit Boards Commonly known as printed circuit boards (PCBs)
Copper track laid on fiberglass
Electronic components are soldered to copper track

51. 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. 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. Tools Meters Ammeters Voltmeters Ohmmeters
Volt-ohm-milliammeters (VOM)
Continuity tester
Oscilloscope

54. 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. Electrical Engineering in Action
Hybrid cars
Combine internal combustion engine and batteries
Regenerative braking
Increased fuel mileage
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