1. ENGR 111 Exam 3 Review Dec. 1, Thu., 8:15-9:45pm Zachry 102 Closed book, closed notes. No calculators allowed. No teaming. Scantrons will be provided. Leave belongings (cell phones, backpacks, etc.) by the stage in front of the class.

2. Topics (Covered in Exam 1) Engineering, Engineering Design DC Basics  KCL, KVL, Ohm’s Law, power, energy, current and voltage dividers, resistors in series and parallel AC Basics  Capacitance, inductance, transformers, RC circuits Semiconductors, Transistors

3. Topics (Covered in Exam 2) Binary, Logic, Memory Elements  Binary representation, Gates, Truth tables, Logic rules, SR Latches, SRAM/DRAM Computer systems, Memory Digital information, Transmission, Spectrum, Modulation  ASCII, images, audio/video, Sampling theorem, Delay, Noise, SNR, Digital vs. analog, AM/FM, Modems, Spectrum sharing

4. True/False Review The sum of currents flowing into a node in a circuit depends on the voltage applied to the circuit components. The power dissipated by a resistor is lower for a 100. V AC source as compared to a 100. V DC source. The ratio of voltages across two resistors connected in parallel depends on the values of the two resistors. A transformer can be used to convert a 120 V AC source to a 12 V DC source. The power dissipated in an ideal inductor is zero.

5. KCL, KVL Given: Va=10.0 v, Vb=5.0 v, Vc=10.0 v; R 1 =10.0 k , R 2 =5.0 k  I 1 =(Va-Vb)/R 1 =(10.0-5.0)/10.0k=0.50 mA I 2 =(Vb-Vc)/R 2 =(5.0-10.0)/5.0k=  1.0 mA I 3 =  I 1 +I 2 =  1.5 mA V AB =Va  Vb=5.0 v, V BC =Vb  Vc=  5.0 v, V AC =Va  Vc=0

6. Resistors in Series and Parallel Which one of the resistors dissipates the maximum power in these circuits? R1=10.0 , R2=20.0 , R3=30.0 .

7. Voltage Dividers What is Vout? What if load is applied?

8. AC The maximum voltage across a light bulb connected to a 120. V AC outlet is … Power consumed in the circuit is …

9. RC Circuits Vs = 27.18 v, R=10.0 k , C=100.  F Thus, RC = 1.00 s Switch closed at t=0.0 s Vc=0.0 V at t=0.0 TimeCurrent through R Right after switch is closedVs/R=2.72 mA t=1.0 sVs/R * 1/e = 1.00 mA t=2.0 sVs/R * 1/e 2 = 1.00/e mA t=20.0 sVs/R * 1/e 20 = 0 mA

10. Digital Information In full HD mode, your 1080p TV displays video at 30 frames/second, with each frame being 1920x1080 pixels, where each pixel is represented by 3 colors, each of 8 bits. How many seconds of uncompressed full HD video can a 50 GB Blu-Ray disk hold?  50  10 9  1920  1080  30  3  8  50  10 9 /(1920  1080  30  3  8)  50  10 9 /(1920  1080  30  3)  None of the above

11. Transmission Which if these are true for digital signal transmission?  Allows accurate reconstruction of signal even in the presence of noise  Eliminates attenuation  Is less efficient than analog transmission  Requires repeaters or regenerators to transmit over long distances

12. Sampling At what rate should a 25 kHz signal be sampled to allow perfect reconstruction?  12,500 samples per second  25,000 samples per second  50,000 samples per second  25,000/sqrt(2) samples per second  None of the above

13. Communication How much time does it take to download a 1 Mb file over a 1000 km long, 100 Mbps fiber optic cable? (Assume speed of light in fiber is 2x10 8 m/s.)  100 ms  50 ms  15 ms (tprop = 5 ms; L/R= 10 ms)  5 ms

14. Compression The size of 16 minute video compressed to 1 Mbps is  16x10 6 bits  128x10 6 bytes  120x10 6 bytes  960x10 6 bytes