1. Lecture 16: Electrical Engineering II EEN 112: Introduction to Electrical and Computer Engineering Professor Eric Rozier, 4/10/13

2. EXAM GRADES

3. Quiz III Grades

4. Midterm Grades Midterm I – Average: C+ – 25% - B+ – 50% - B- – 75% - C- Midterm II – Average: B – 25% - A – 50% - B – 75% - C

5. Midterm II Grades

6. Midterm I & II Grades

7. Course Grades Average: A- 25% - A 50% - A- 75% - B

8. Course Grades

10. The Importance of Trust Sarbanes-Oxley Act HIPAA California Proposition 11 FISMA Massachusetts 201 CMR 17.00 Over 10,000 regulations

11. Users expect data to be stored indefinitely…

12. Reliability What responsibilities do we have as engineers to preserve information? Should we be liable if our systems fail in these ways? What limits should there be to liability? Can a system ever be fully reliable? What responsibility do we have to report the limits to our systems reliability?

13. High Frequency Trading Algorithmic trading, seeks to exploit small differences in prices, millions of programs running How do they interact? How does something written by Company A affect something written by Company B?

14. High Frequency Trading 2010 Flash Crash – largest intraday point loss – Losses recovered in minutes, but scared regulatory bodies US SEC and CFTC consluded that HFT contributed to the volatility.

15. High Frequency Trading SEC and FTC stated – “market makers and other liquidity providers widened their quote spreads, reduced liquidity, and withdrew from the market” Some signal set off their algorithms, caused a joint movement which helped cause the crash

16. High Frequency Trading What responsibility do we have to prevent disasters? What happens when our duty to our employer might conflict? How do we weigh our responsibilities?

17. The broader world is complex Critical thinking Awareness of situations and consequences Working with regulators, and employers Maintaining integrity

18. ELECTRICAL ENGINEERING

19. Resistors What do the bands mean?

20. Ohm’s Law Resistance, Voltage, and Current are related… V – I – R –

21. POWER!!! P = V I V = I R, so… – P = (I R) I = I^2 R I = V/R, so… – P = V (V/R) = V^2/R

22. Diodes

24. LED Light Emitting Diode – Diode that emits light (fancy that!) – Low power, bright – Come in various colors Using LEDs – Use in correct orientation – Use a current limiting resistor!!!

25. LED History Invented in 1962 by Dr. Nick Holonyak while at General Electric Dr. Craford (Dr. Holonyak’s student) invented the first colored LED First LEDs produced by Monsanto Company in 1968

26. LEDs

29. Semiconductors Electrical conductivity between a conductor and an insulator Conductivity increases with temperature P-type semiconductor – Excess holes N-type semiconductor – Excess free electrons “Doping” sets these properties

30. Doping Not just for the Tour de France! Introduce impurities – Gallium Arsenic gas very popular Grow silicon in an environment with the impurities in certain concentrations

31. LEDs

32. P-Type? HOLES!

33. N-Type? FREE ELECTRONS!

34. P-Type? HOLES!

35. N-Type? FREE ELECTRONS!

36. LEDs

37. Semiconductors Both P and N junctions are relatively conductive… under the right circumstances Junctions get depleted of charge

38. LEDs

39. Often used as indicator lights More recently for – TVs – Flash lights – Light bulbs – Jumbo-tron displays