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ECE 2006 UMD Fall, 2006
Name:__________________________EXAM I: 100 Points, Show work for partial credit.
1a. Given I(t) in the graph below, find:
(7pts) The charge, q(t), for 2<t<4 seconds (6pts) Also, compute q(4 seconds)
Answers:q(t) = -1.25t2 +10t -10 + q(0) mC, 2 < t < 4 sec; q(4) = 10 mC + q(0)
1b. The charge delivered to the resistor shown below is described by the following equation: q(t) = -120 e-5t microcoulombs
(6pts) Calculate I(t).(6pts) Also, for the diagram shown, if V = 1.2 e-5t Volts, find the value of R, in Ohms using
your value for I(t).
Answers: I(t) = 600 e-5t microamperes; R = 2 k-ohm
Scott Norr Page 1 5/25/2023
ECE 2006 UMD Fall, 2006
2a. (15pts) In the diagram, find the value of R2, in terms of R1, that will satisfy Req = 2R1.
Answer: R2 = 2R1
2b. (10pts) Find a value for Ra in the diagram that makes Req = 10 Ohms
Answer: Any value, 0 <= Ra < ∞
Scott Norr Page 2 5/25/2023
ECE 2006 UMD Fall, 2006
3. (25pts) Solve by any method for: Io: Vo:
Answers:Vo = 6.5 volts ; Io = -3.5 mA
Scott Norr Page 3 5/25/2023
ECE 2006 UMD Fall, 2006
4. Solve for:(15pts) Vo, by any method
(10pts) The power supplied or absorbed by the source, V2.
Answers:
Vo = 7 volts; PV2 = -50 W
Scott Norr Page 4 5/25/2023
ECE 2006 UMD Fall, 2006
Bonus 1: Apply Ideal Op Amp Assumptions to the amplifier circuit below. Find:a. An equation for Vo, in terms of the input voltage, Vs.b. If Vs = 2 volts, calculate Vo.c. For Vs = 2 volts, calculate Io. (If you’re unable to answer part b., you may assume a value for
Vo and proceed for full credit)
Answer: Vo = 40 - 11Vs volts; Vo = 15 volts (saturated); Io = 3.100 mA (3.1083 mA if you really know your stuff)
Scott Norr Page 5 5/25/2023
ECE 2006 UMD Fall, 2006
Bonus 2: For the following steady-state DC circuit:
5 Pts – Find Ix10 Pts – Find Vx 5 Pts – Find V-thevenin between A and B 5 Pts – Find R-thevenin between A and B
Answers:
Ix = 2 amps; Vx = 30 volts; Vthev = 30 volts; Rthev = 15 ohms
Scott Norr Page 6 5/25/2023