Fundamentals of Electrical Engineering / Tutorial
1
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T.6.
Capacitors and Inductors
T.6.1 Problems
Problem 1
The voltage waveform left is applied across a 30µF capacitor. Draw the current waveform through
it.
Problem 2
The voltage across a 2-mF capacitor is shown.
Determine the current through the capacitor.
Problem 3
A 4-mF capacitor has the current waveform shown in the figure. Assuming that v(0)=10V, sketch the
voltage waveform v(t).
i (mA)
15
10
5
0 0
0
–5
8 t(s)
2
4
6
8
–10
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Michael E. Auer
Carinthia University of Applied Sciences
Fundamentals of Electrical Engineering / Tutorial
2
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Problem 4
Find the voltage across the capacitors in the circuit under dc conditions.
30 Ω
30V; 40V
Problem 5
Determine the equivalent capacitance for each of the circuits.
3F; 8F; 1F
______________________________________________________________________________________________
Michael E. Auer
Carinthia University of Applied Sciences
Fundamentals of Electrical Engineering / Tutorial
3
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Problem 6
Find Ceq in the circuit if all capacitors are 4 µF
Ceq
2.18µF
Problem 7
The equivalent capacitance at terminals a-b in the circuit is 30 µF. Calculate the value of C.
20µF
Problem 8
For the circuit right determine:
(a) the voltage across each capacitor,
(b) the energy stored in each capacitor.
60V; 60V; 20V; 40V; 7.2mJ: 3.6mJ; 1.2mJ; 2.4mJ
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Michael E. Auer
Carinthia University of Applied Sciences
Fundamentals of Electrical Engineering / Tutorial
4
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Problem 9
Three capacitors, C1 = 5 µF, C2 = 10 µF, and C3 = 20 µF, are connected in parallel across a 150-V
source. Determine:
(a) the total capacitance,
(b) the charge on each capacitor,
(c) the total energy stored in the parallel combination.
35 µF; 0.75mC; 1.5mC; 3mC; 394mJ
Problem 10
An inductor has a linear change in current from 50 mA to 100 mA in 2 ms and induces a voltage of
160 mV. Calculate the value of the inductor.
6.4mH
Problem 11
The current through a 10-mH inductor is shown. Determine the voltage across the inductor at t=1, 3,
and 5ms.
i(A)
20
0
2
4
6
t (ms)
100V; 0V; -100V
Problem 12
Determine Leq at terminals a-b of the circuit.
7.78mH
______________________________________________________________________________________________
Michael E. Auer
Carinthia University of Applied Sciences
Fundamentals of Electrical Engineering / Tutorial
5
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Problem 13
Under steady-state dc conditions, find i and v in the circuit.
6mA; 120V
Problem 14
Find vC, iL, and the energy stored in the capacitor and inductor in the circuit under dc, steady-state,
conditions.
4A; 0V; 4J; 0J
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Michael E. Auer
Carinthia University of Applied Sciences