=========================preview======================
(elec101)[2011](s)midterm2~2286^_13620.pdf
Back to ELEC101 Login to download
======================================================
ELEC 101 (L2) Quiz 2 April 19, 7pm-8:15pm

IDNo. _
Chinese Name: _
Number Max Score Score
1 10
2 10
3 12
4 4
5 10
6 12
7 12
Total 70

Useful information: 109 ~ G 10-3 ~ m

10-12 ~ p
Vc(t)~ Vc(O)+ [vc("')-Vc(O)l{l-e-~]
IL(t)~ IL(O)+[ILH-IL(O)l{l-e -~]

This is a CLOSED book and CLOSED notes examination.
ELEC 101 (L2l-----Quiz 2 April 19, 7pm-8:15pm
3. Assuming that the switch has been closed for a long time, 12 marks at time t = 0 the switch is opened in Fig. P-3.
(a)
Find V1(0 ),11(0 )

(b)
Find V1(0+), 11(0+) t=o


3mA
Co-)
r-, Co -) ~ ():I ) ~1t1
Fig. P-3
[1", CO') -=-"J M A 1#
V, (0-) ":-(~,.., _ '2.-~) ,(7,)
jV, CO -)"-2-m VJ

ff
G h) 1(C0" ) ~ t-, C0 -)
f ~({O-t ) = J.-"., A I
tt V,C Of) .~ -J,{ 0+) I C-,..) IV;C 0"<) :: -4-,., l/]
If


4. Find the impedance ZAB, when ro = 1M rad/s in Fig. P-4. 4 marks
,
-~
A0----
Fig. P-4
5. Find tl,le simplest form ofthe unknown elements in ZI 10 marks
(i.e. find the values of R, L and/or C) in Fig. P-5.
(a)
when I1(t) = cos(106 t) A.

(b)
when II(t) = cos(l06 t -90 ) A.


J
'];-;.. I
Co-/) Lo cos(106 t) V
I L-o'
--I L-O .#
?' t &,
:::.-(
it-l-,
I

we.::: (


(n IMf C:-I M. I~
--V'v ll----
-----*(
IL -'It;) 0. A
I L-c>? ~

l' -I-l, =-( L -9'0

I -~-l, ~ I
c-I -;. 0 fl -==-!) R..:-O .n J
---~---
!
-------'4

ELEC 101 (L2) Quiz 2 April 19, 7pm-8:15pm
6. Find Vl(t) in Fig. P-6. 12 marks
cos(106 t -45) V


Fig. P-6
v,et):o. I IN> C10 6 -t -If SO)j/l
\
L.------~!f

ELEC 101 (L2)_ Quiz 2 April 19, 7pm-8:15pm
7. Find V1 in phasor fonn indicated in Fig. P-7. 12 marks

Fig. P-7
"2-
VI
/1"f' o-j
;y ~

,.
....-J.,... 0
-f-J.. VI
l-iV; -
V, ----f .
7--t?
::I
,..
[Vi -0, '-I-Cf. 7 L "),6, 6 v
14f
----END ----

ELEC 101 (L2) Quiz 2 April 19, 7pm-8:1Spm
2. Assuming that the initial inductor current h(O) is aA, 10 marks at time t = athe switch is closed in Fig. P-2.
(a) Find h(t) for t > O.
t=O
(b) Plot h(t) for t < aand t 2:: O.
2V
( fA) T" Co) -=-0
Fig. P-2
"2
A

71.-CoO) ~ -;;;. :;. O. 7--
= I M. >~
t
..---
[ 0.2-0] CI e /~)
!l-(t) :. 0 +-.
,_Lt-Ct) ~ 0,. 1.-o_,.._~_~_~_~_A~___')L{"rH
1

~--------I"--=----------=.-
o

HKUST 2011 Spring Quiz2-3 Kwok
ELEC 101 (L2) Quiz 2 April 19, 7pm-8:15pm
1. Assuming that the initial capacitor voltage Vc(O) is 0 Volt, 10 marks at time t = 0 the switch is closed in Fig. P-1.
(a)
Find Vc(t) for t > O.

(b)
Plot Vc(t) for t < 0 and t ~ O.


2V
C(i\) Vc-(0) :: 0

Ve-toO)':' 2.V
'C ~ CL.:J~) ( 1M-) :; (J" 0' S
_ -t
vert).;; () +[ '1 --0 J CI -e o~v,)
l_v_cC_t_)-_-_2_-_2-_e_-_b_:O_7_v~t
cb)

------:::::--:-----

HKUST 2011 Spring Qwz2-2 Kwok