prelim2_sp2011_soln

# prelim2_sp2011_soln - Y our Name 50 1 ~l lpt P relim 2 ECE...

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Your Name: 5 0 1 ~l (lpt) Prelim 2 ECE 2100, spring 2011, Professor Molnar The exam will last 2.5 hours, you are permitted 2 sides of 8.5"x11" crib sheet to be turned in for Spts. You may also use a calculator. Scrap paper is provided and should be attached: show your work for partial credit. However, answers should be written in the space provided: if we have to go looking for your answer, you will lose 1 point off that answer! If you get stuck on any given part, move on, and come back later: REALLY make sure you look at every part of this exam. 1) (2pts) What is the magnitude and phase of the complex number 1+j ~r: 17 / Mag = U 2.. ,phase = '/4 2) (4 pts) Ifa component driven by voltage Vet) = 14Vcos(rot), absorbs a current of I(t) = 1Acos(rot -1[14), what is the instantaneous power delivered? What is the average power? pet) = 5 wCI f(6'72w0 t 5' 7" ote lwt) ,Pavg= So C\l 3) (4 pts) Your friend from Harvard claims that this is a non-inverting amplifier with gain RF/R1. Is it? Vout ,- Vin Circle one: Y 1 ~ If not, then, what is the gain? (assume the op-amp is ideal) !L Gain = Vout/Vin = _

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4) When measuring from a coaxial cable with one end disconnected, and the other driven by a source with open circuit voltage Vs(t), and thevenin resistance of son, you observe that the input voltage take the form Yin = 12 (Vs(t) + Vs(t+T)). (the signal propagates down the cable to the end, and is reflected, with a round-trip time ofT) Vs(t) - - a. (2pts) 1fVs(t) =1 Vcos(wt), what will lin(t) be in terms ofT and w? (hint: what is lin in terms ofVs and Yin?) _)\') i A((6'} ~r- -(O'j(\J.Jt ","wi I) lin(t) =_0_"" _ b. (4pts) Describe the impedance, Z=Vinl1in
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## This note was uploaded on 06/10/2011 for the course ECE 2100 taught by Professor Kelley/seyler during the Spring '05 term at Cornell.

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prelim2_sp2011_soln - Y our Name 50 1 ~l lpt P relim 2 ECE...

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