Lecture 21 - Electrical Engineering - Part 1 Introduction to Engineering Approximate Running Time - 23 minutes Distance Learning / Online Instructional Presentation Presented by Department of Mechanical Engineering Baylor University Procedures: Select “Slide Show” with the menu: Slide Show|View Show (F5 key), and hit “Enter” You will hear “CHIMES” at the completion of the audio portion of each slide; hit the “Enter” key, or the “Page Down” key, or “Left Click” You may exit the slide show at any time with the “Esc” key; and you may select and replay any slide, by navigating with the “Page Up/Down” keys, and then hitting “Shift+F5”.

Lecture 21: Electrical Engineering Topic 1 Voltage and Current Professor Brian Thomas Speaking

Electrical Engineering: Information and Power Electricity Basics Outline Electrical Engineering: Information and Power Electricity Basics Charge Current, Voltage, Power AC, DC, grid power

Information and Power Information Power Radio Television Internet Cellular telephone Satellites Embedded systems Fiber optics, lasers Power Lighting Appliances Motors Heating Welding & manufacturing On grid / off grid EMP

Charge Electricity Basics The smallest bit of charge is the charge of an electron Charge flowing is called ____________ Charge accumulated produces ___________

Electrons are free to flow in metals and other “conductors” Electric Current “Free” electron Atom Electrons are free to flow in metals and other “conductors” Materials where charge may not flow are ________________ An electron removed from a neutral atom leaves behind a _____________ By convention: electrons have negative charge, protons (and holes) have positive charge

Electric Current 1 “Coulomb” of charge is 6,241,506,360,000,000,000 electrons If 1 Coulomb flows through a wire in 1 second, we say the current is 1 ampere or 1 “amp” Current always __________ ____________

Brain cell synaptic currents (10-13 A) Current Magnitudes Brain cell synaptic currents (10-13 A) Integrated circuits currents (10-4 A) Threshold of human sensation (10-3 A) Causes Ventricular fibrillation (10-1 A) Household appliances (10 A) Large Industrial Equipment (100 A) Lightning Bolt (1000 A)

Electrostatic force gives rise to stored energy Electrostatic Forces Electrostatic force gives rise to stored energy Stored energy mental images __________________ Water pressure (or height of column of water)

Electrostatic Force Example

Voltage arises from accumulated charge being _________________ Opposite Charges Attract Positive likes negative and visa versa Energy is required to keep them apart Like the ends of a rubber band Rubber bands can be stretched to different lengths “Voltage” is a measure of how much energy each coulomb of charge contains

1 “volt” means each coulomb of charge can release 1 Joule of energy Voltage 1 “volt” means each coulomb of charge can release 1 Joule of energy A 12 Volt battery will produce 12 Joules of energy for every coulomb of electrons delivered 120 VAC

Voltage exists between two points, not at an individual point The earth is a common reference point “Ground” Voltages with respect ground are like rubber bands with one end on the ground

Power is the rate at which energy is transferred Electric Power is found by multiplying _______________________

Power Question: How much power is supplied to a belt sander that draws 15 amps using “wall” voltage?

AC, DC, and all that DC stands for _____________ and means the voltage and current are constant All batteries supply DC power “Cigarette Lighter Power” is DC AC stands for ________________ and means that the voltage and current “alternate” back and forth Grid-supplied electric power is AC, cycling 60 times every second, or at 60 Hz.

This Concludes Lecture 21