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

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

4. 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

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

6. 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

7. 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 __________ ____________

8. 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)

9. 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)

10. Electrostatic Force Example

11. 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

12. 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

13. 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

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

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

16. 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.

17. This Concludes Lecture 21