Problem 7.90 PSpice|Multisim
The energy stored in the capacitor in the circuit is zero at the instant the switch is closed. The ideal operational
amplifier reaches saturation in 18 ms .
Part A
What is the numerical value of R in kilo­ohms, if C = 310 nF ?
ANSWER:
R
= kΩ Problem 8.2 PSpice|Multisim
The circuit elements in the circuit in are R = 100 Ω ,
C = 5 μF , and L = 200 mH . The initial inductor current is
­0.3 A, and the initial capacitor voltage is 25 V.
Part A
Find the expression for v(t) for t
≥ 0
.
ANSWER:
70, 000te
35, 000te
70, 000te
70, 000te
35, 000te
35, 000te
70, 000te
35, 000te
−1000t
−1000t
−1000t
−1000t
−1000t
−1000t
−1000t
−1000t
+ 50e
− 50e
+ 25e
− 50e
+ 25e
+ 50e
− 25e
− 25e
−1000t
−1000t
−1000t
−1000t
−1000t
−1000t
−1000t
−1000t
V
V
V
V
V
V
V
V
Problem 8.7
The voltage response for the circuit in is known to be −80t
−80t
v(t) = D1 te
+ D2 e
, t ≥ 0 , where t is in seconds. The initial current in the inductor (I0 ) is ­25 mA , and the initial voltage on the capacitor (V0 ) is 5 V . The resistor has a value of 50 Ω .
Part A
Find the value of L.
Express your answer to three significant figures and include the appropriate units.
ANSWER:
L
= Part B
Find the value of C .
Express your answer to three significant figures and include the appropriate units.
ANSWER:
C
= Part C
Find the value of D1 .
Express your answer using three significant figures.
ANSWER:
D1
= V/s Part D
Find the value of D2 .
Express your answer using three significant figures.
ANSWER:
D2
= V Part E
Find i C (t) for t
≥ 0
+
.
Express your answer in terms of t, where t is in milliseconds.
ANSWER:
iC
= mA Problem 8.24 PSpice|Multisim
The initial energy stored in the circuit in the figure is zero. At t
circuit. The value of the resistor is 400 Ω .
Part A
Find v(t) for t
≥ 0
;
ANSWER:
32(e
16(e
16(e
32(e
16(e
16(e
32(e
32(e
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
+e
−e
−e
−e
+e
+e
+e
−e
Part B
Find i R (t) for t
ANSWER:
≥ 0
;
−40,000t
−80,000t
−40,000t
−80,000t
−80,000t
−40,000t
−80,000t
−40,000t
) V
) V
) V
) V
) V
) V
) V
) V
= 0
, a dc current source of 24 mA is applied to the
40(e
40(e
20(e
20(e
20(e
20(e
40(e
40(e
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
− 2e
+ 2e
−e
+ 2e
−e
+e
−80,000t
−80,000t
− 2e
+e
−80,000t
−80,000t
−80,000t
−80,000t
) mA
) mA
−80,000t
−80,000t
) mA
) mA
) mA
) mA
) mA
) mA
Part C
Find i C (t) for t
≥ 0
;
ANSWER:
−8e
−8e
−8e
−4e
−4e
−8e
−4e
−4e
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
−20,000t
+ 32e
− 32e
+ 16e
− 32e
+ 16e
− 16e
+ 32e
− 16e
−80,000t
−80,000t
−80,000t
−80,000t
−80,000t
−80,000t
−80,000t
−80,000t
mA
mA
mA
mA
mA
mA
mA
mA
Problem 8.31 PSpice|Multisim
The switch in the circuit in has been open for a long time
before closing at t = 0.
Part A
Find i o (t) for t
≥ 0
.
ANSWER:
3 − 1200te
3 − 1200te
6 − 1200te
3 − 1200te
6 − 1200te
3 − 1200te
6 − 1200te
6 − 1200te
−800t
−800t
−800t
−800t
−800t
−800t
−800t
−800t
+ 6e
− 6e
− 3e
+ 3e
+ 6e
− 3e
+ 3e
− 6e
−800t
−800t
−800t
−800t
−800t
−800t
−800t
−800t
A
A
A
A
A
A
A
A
Problem 8.39
The current in the circuit in the followin figure is known to be −2000t
−2000t
i = B1 e
cos1500t + B2 e
sin1500t, t ≥ 0.
The capacitor has a value of 80 nF; the initial value of the current is 6 mA ; and the initial voltage on the capacitor
is ­21 V .
Part A
Find the value of R .
Express your answer with the appropriate units.
ANSWER:
R
= Part B
Find the value of L .
Express your answer with the appropriate units.
ANSWER:
L
= Part C
Find the value of B1 .
Express your answer with the appropriate units.
ANSWER:
B1
= Part D
Find the value of B2 .
Express your answer with the appropriate units.
ANSWER:
B2
=