# Homework Help: Practice Exams

1. Jul 29, 2012

### Celostrophus

These exams are merely help for studying for the final in this class. Completing them will not give me any credit whatsoever or affect my grade in the course. The only problem is that our instructor did not give us answers to the tests so we have no idea whether or not we worked the problem correctly. If someone could provide the answers to these problems, not the work that goes along with it, I would be forever grateful. If you need to see an attempt at the solutions before you can give me JUST THE ANSWERS. Then I will upload a PDF for each exam of my attempt at the solutions.

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• ###### final exam SS10.pdf
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2. Jul 30, 2012

### Staff: Mentor

Yes, we need to see an attempt first, according to the rules of PF (to see the rules, click the Rules button near the top of the window).

3. Jul 31, 2012

### Celostrophus

EXAM SS09

Problem 1:
In = -1 A
Rth = 10 Ω

Problem 2:
Voc = 1.25 V
Rth = 7.5Ω

Problem 4:
0 < t < t0
VL(t) = 15e-1000tV

t > t0
VL(t) = 10e-20000t

Problem 5:
Vout = 0V

Problem 6:
I3 = 4/3 - 8/3j A

Vz = 80 + 40j V

Problem 7:
Zeq = 10 + ω(-10,000j + 1x10-62)-1

Not sure how to graph it.... could use some help here.

Problem 8:
iavg(t) = -10/3 A
ieff = 17.5 A

Problem 9:
a) Vs(t) = 100√2cos(ωt)

b) Is = 0.857∠-30.97° A

c) 85.7∠-30.97° VA

d) pF = 0.857

e) z = -818.33Ω

Problem 10:
zL = 5 + 3j Ω

Pmax = 367.65 - 220.6j VA

4. Jul 31, 2012

### Celostrophus

EXAM SS10

Problem 1:
Using Mesh Currents:
I1 clockwise in bottom left area.
I2 clockwise in bottom right area.
I3 clockwise in top area.

Vx = 5Ω*I3
VB - VA = 2V
VA - VC = VX
VC = 25Ω*I2
VA = -10Ω*I1
VB = 20Ω(I1 - I2)
I2 = 0.2VX + I3

Problem 2:
Vth = 13.33V
Rth = 8.33Ω

Problem 3:
Vc(t) = 7.59 - 7.59e-50,000t
Vc(t) = 7.59e-50,000t

Problem 4:
Vout(t) = Vin(t)/2 - 2.5

Problem 5:
a) iavg(t) = 5A
b) Ieff = 10/√3 A
c) 500/3 W

Problem 6:
S = 0.77 - 1.15j

Problem 7:
a) 1 W
b) 1.28 W
c) 0.781
d) C = 45.1μF

Problem 8:
C = 40μF
R = 12.5Ω
Pmax = 1.25W

Last edited: Jul 31, 2012