## EEGR2111, Fall 1996

### Homework Solutions

• Homework set 1:

1.3-2 a) 2E-6, 0, 4E-6, -3E-6, 0 c) 4E-6 d) 2.5E-7
1.3-4 k1=2, k2=-4/3
1.5-2 0.58 day
1.6-4 a) Ps=8100W, Pt=220W b) 2883 kJ
2.3-2 no
2.4-2 20 cos2t mW
2.5-2 P=706W, R=63 ohm
2.5-3 a) 2.5 W b)4W
2.10-1 i(1)=.002 A, i(4)=3mA

• Homework set 2:

3.3-3 i=2mA; v1=-8; p10k=40mW, p4v1=-64mw, p12v=24mW, p4k=16mW,p8v=-16mW
3.4-2 R=13.5 or 6
3.6-7 is=16, v=192
3.6-11 p8ma=128mW, p12ma=-192, p6k=42.7mW, p12k=21.3mW
3.6-16 vx=3, p=45mW
3.6-21 req=12, i=0.67A , v=5.33V
4.3-4 v1=-0.1V, v2=-0.2V, v3=-0.4V, p1ma=-0.2mW
4.5-7 i=2.4A
4.7-3 i1=-0.5A
4.7-21 gain=-170, g=0.037 A/V

• Homework set 3:

5.3-2 2.19 A
5.4-4 V10v + V4A = 10 + 16 = 26 V
5.5-2 90V, 8 ohm
5.5-10 30 V, 30 ohm
5.5-12 Voc=-3, Isc=0.02A, so Vt=-3 V, Rt=-150 ohm
5.6-3 a) 5.4A, 16 ohm b) 118W
5.7-3 P=v2 / (RL + RS) is max when denominator is min
6.4-1 a) v2=i1 * Rc = 0 * Rc = 0 b) KCL @ V1
6.5-9
6.5-15 v=5, i= 0.2mA
6.6-4 See Fig. 6-11 (f), with any values of R1, R2 where R2/R1=5

• Homework set 4:

7.3-3

0 < t < .5, 200 t2;
.5 < t < 1.5, -500 t2 + 1000 t - 250;
1.5 < t <2.5, 500 t2 - 2000 t + 2000;
7.4-2 i(t) = 0.2 e-4000 t, w(0) = 0, w(.01) = 0.000125 J
7.5-4 V12 = 20V, V6 = 40V, V5 = V1 = 40V
7.5-2 4 uF
7.6-3 v(.001) = 20 mV, v(.006) = 40 mV
7.6-5 i(1 us) = -1.2 uA, i(3 us) = -1.6 uA
7.8-2 a) 36.7 mH, b) 14 mH
7.9-1 v(0+) = 16 V, dv(0+)/dt = -0.1 V/s
7.9-4 v(0+) = 17 V, dv(0+)/dt = 3000 V/s
7.10-2 v(t) = 0 for t < 0, v(t) = 3 V for t > 0

• Homework set 5:

8.4-1 2 e-2000 t
8.4-6 8 e-4 t
8.5-4 2.67 e-1.67 t
8.7-4 2.5 uF
8.8-4 @ t=2s, 2700V, 1.2 J
8.9-1 v(t)= -35 e- t , i(t)= 10 e- t
8.9-3 v(t)= 6 e- 2 t
8.10-1

t < 0, v= 10
0 < t < 0.1 , v= 10 e- 20 t
0.1 < t , v= 1.35 e- 25 (t - 0.1)
8.10-4
t = 0+, v= 0.6 V
0.01 < t < 1 , v= 0.6 e- 2 (t - 0.1)

• Homework set 6:

9.3-1 v(t) = 2.5 ( 1 - e-1000 t ), i(t) = 0.05 ( 1 + e-1000 t )
9.3-7 Should be Meg ohm not milli; v1(t) = 20 + 80 e- t / 4, v2(t) = 20 - 20 e- t / 4
9.3-11 Should be Meg ohm not milli;

0 < t < 30 , v(t)= 70 - 50 e- t / 40
30 < t , v(t)= 20 + 26.4 e- (t - 30) / 10

9.4-1 v(t) = 6.67 + 5.33 e- 1.5 t
9.4-6 i(t) = 2( 1 - e- 500 t) , 9.2 ms
9.5-2 v(t) = 10 ( 1 - e- 100 t)
9.5-6 v(t) = 7 - 5 e- 12 t
9.5-12
t < 0 , v(t)= 0
0 < t < 0.3 , v(t)= 4 - 4 e- 2.5 t
.3 < t , v(t)= 2.11 e- 2.5 (t - 0.3)

9.7-4 v(t) = -5 e- 2 t + 5 cos(2t) + 5 sin(2t)

• Homework set 7:

10.3-1d2v/dt2 + 3000 dv/dt + 1.02 x 108 = 1.0 x 108 Vs
10.4-3 s2 + 400 s + 30000 = 0, s= -100, -300
10.5-3 v(t) = -1 e- t + 3 e- 3 t
10.5-4 i1(t) = 3 e- t / 6 + 8 e- 2 t, i2(t) = - e- t / 6 + 12 e- 2 t
10.6-3 v(t) = 1012 t e- 5 x 107 t
10.7-6 v(t) = 544 e- 267 t sin(1257 t)
10.9-1 i(t) = { -16.67 e- 2 x 105 t + 16.667 e- 8 x 105 t + 4 } mA
10.9-6 v(t) = -0.09 e- 105 t sin(2 x 105 t) + 0.6 V
10.9-16 v(t) = 100 + e- 375 t {-100 cos(832 t) -45.1 sin(832 t)}
i(t) = 6 e- 375 t sin(832 t)

• Email: tpweldon@uncc.edu