1. ECE 2006 CIRCUIT ANALYSIS University of Minnesota - Duluth Lecture 1

2. Instructor: Scott R.Norr, PE BSEE – North Dakota State University – 1986 Registered Professional Engineer, MN –1994 Minnesota Power – 1986 to 1997 ECE Dept. at UM – Duluth - 1999 to Present

3. Course Details: Textbook: Alexander/Sadiku – Fundamentals of Electric Circuits. 2 nd Ed. Lab Place/Time: Tuesdays – MWAH 391 Course Assessment: Homework: 15% Labs: 25% Midterms: 40% Final: 20%

4. TOPICS Fundamental Laws of Electricity Circuit Theory Analysis Methods Operational Amplifiers Energy Storage in Caps and Inductors Transient Circuits AC Circuits

5. A Crude History of Electricity 600 BC: Ancient Greeks rub amber on cat fur to produce static charge Circa 0 AD: Persians in present-day Iraq invent the battery for unknown (probably medical) purposes 1720’s: Stephen Gray shows that static charges can be ‘conducted’ from point to point

6. History (Cont.) 1750’s: Benjamin Franklin’s One Fluid Theory of Electricity unifies scientific approaches to electricity and forms the foundation of modern electrical theory 1800’s: Alessandro Volta makes his Voltaic Pile using zinc and copper disks submersed in an electrolytic solution (acid), thus re-inventing the battery, 1800 years after the Persians

7. History (Cont.) 1820’s: Hans Oerstad discovers electromagnetism with his famous “compass and current- carrying wire” experiments –Andre-Marie Ampere defines electric current and electromagnetism, invents the ammeter –Georg Ohm delivers his theory of electricity, including what later became Ohm’s Law 1830’s: Michael Faraday enters the game and things get intense

8. Physics of Electricity Charge (q) – fundamental property of atomic structures; measured in Coulombs –One electron has a charge of -1.602 x10 -19 C Electric Current (i) – measures the rate of change in Charge; unit is Amperes (C/s) –Relationship: i = d q/ d t

9. Physics - Continued Voltage (v) – The Electromotive Force (emf) required to move Charge around a circuit. Indicative of the Electric Field. Also called Potential Difference; measured in Volts (J/C or N-m/C) –Relationship to charge: v = d w /d q

10. Physics – Continued Some More Power (p) – Rate of change in work (the expending of energy in time); measured in Watts (J/s) p = dw/dt = dw/dq * dq/dt = vi

11. Electric Conventions: Current Convention:

12. Electric Conventions (Cont.) Voltage Rise/Drop Convention

13. Electric Conventions (Cont.) Source/Load Convention

14. Fundamental Laws Ohm’s Law: V = I*R Kirchoff’s Laws: –Voltage: Sum the voltages around a loop to Zero –Current: Sum the currents around a node to Zero Power Equation: P = V*I

15. Maximum Power Transfer Power Transfer is maximized when load impedance equals source impedance

16. Laboratory Equipment Oscilloscope –1 M-Ohm Impedance –“Shunt” Device –Measures Voltages –Always measure voltages with respect to scope ground

17. Laboratory Equipment (Cont.) Multimeter –Measures Voltage, Current, Resistance, etc. –“Shunt” Device for Voltage (High Impedance) –“Series” Device for Current (Low Impedance) –Acts as a DC source when measuring Resistance –NEVER measure resistance on an Energized Circuit

18. SAFETY CONTACT WITH ELECTRIC CURRENT CAN CAUSE DEATH As little as 100 milliamperes (0.1 Amp) of electric current can kill, if it travels across the heart

19. SAFETY (Cont.) Follow Instructions, Ask for Clarification Know where Safety Equipment is Located - Fire Extinguishers, Telephones, Fire Blankets, Eye Wash Stations, etc. Always Assume an Electric Circuit is Hot (Energized) and Dangerous and Act Accordingly

20. SAFETY (Cont.) Keep Work Areas Clean and Uncluttered Double Check Circuit Wiring before Energizing Never Work Alone Wire with One Hand - Minimizes exposure to the Heart

21. SAFETY CONCLUSIONS Always understand the Laboratory Procedures before touching anything. Always assume that electric circuits are potentially live and dangerous. Make sure there are adequate life saving resources available and know how to use them.

22. Resistor Color Code