CONFIDENTIAL
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UNIVERSITI TUN HUSSEIN ONN MALAYSIA
F'INAL EXAMINATION
SEMESTER I
SESSION 201212013
COURSENAME
ELECTRIC CIRCUITS /
ELECTRIC CIRCUIT THEORY
COURSE CODE
BEL 10103/BEX 10103/BEE l1 13
PROGRAMME
BED/ BEB/ BETV BEC/ BEU/ BEE
EXAMINATION DATE
JANUARY 20 13
DURATION
3 HOURS
INSTRUCTION
ANSWER FIVE (5) QUESTIONS
ONLY
THIS OUESTION PAPER CONSISTS OF TEN (TO) PACES
CONFIDENTIAL
BEL IOIO3/BEX IOIO3/BEE I I I3
Q1
(a)
Mention the difference between dependent and independent sources and give
example for each ofthem.
(3 marks)
(b)
The pin diagram of a resistance anay is shown in Figure Ql(b). Find the
equivalent resistance between the following nodes;
(i)
(iD
(iiD
I
and 2
(2 marks)
I
and 3
(2 marks)
2 and 4
(2 marks)
Q2
(c)
Two devices are rated as shown in Figure Ql(c). Find the value oithe resistors
Rr and R2 needed to power the device using a 20 V battery.
(7 marks)
(d)
Find the value ofR. ifthe current flow through the galvanometer, C in Figure
Q1(d) is equal to zero.
(4 marks)
(a)
Three devices with Pr Watts, P2 Wafts and Pl Watts, respectively, are connected
in parallel to a common voltage source. Prove that the total Power is equal to
Pr= Pr+P2+Pt.
(5
(b)
narks)
Three identical light bulbs each rated as 240V AC,40W are connected in series
to 240V AC supply.
(i)
What is the power consumed by each bulb?
(4 marks)
(iD
Would the brightness ofthe bulb be the same ifthey are connected in
parallel? Prove and explain.
(2 marks)
(iiD
Will the light bulb's total power in
series
will equal to the total power
when they are connected in parallel? Justify your answer.
(2 marks)
(c)
Find L for the circuit shown in Figure Q2(c).
(7 marks)
BEL 10103/BEX 10103/BEE I I l3
Q3
(4,
A typical transistor amplifier is shown in Figure Q3(a). Determine the amplifier
gain, which is the ratio of the output voltage to the input voltage.
( l0 marks)
(b)
Use the mesh analysis to determine i!, ib and i" for the circuit in Figure Q3(b).
(10 marks)
Q4
Qs
(a)
Norton's theorcm can be used to simplify circuit analysis By using this theorem,
prove that R1 = 50 O and lr'r = -0.1 A for the circuit in Figure Q4(a) at a - b
terminals.
(8 marks)
(b)
Find the Thevenin €quivalent resistance, Xrr and Thevenin voltage, trrr between
terminal a and b in Figure Q4(b).
(12 marks)
(4,
Determine the equivalent inductance tdq between terminals a and b in Figure
Q5(5)
(5 marks)
(b)
The cuffent flowing through a l0 FF capacitor having terminals labeled a and b
A for t > 0. Civen that vdr(o) = 0, find an expression for
is ;a = 6.3
"*0,-rOOO/)
,,b(r) for , > 0, Also determine the energy stored in the capacitor for I : co.
(5 marks)
(cl
The inductor in Figure Qs(c) has been connected to the independent source for a
long time.
(i)
Determine l(t)
forr >0.
(7 marks)
(ii)
Ifthe voltage source 6u(t)
is tumed
off, does the initial inductor current
change?
(iii)
Cive ONE
(l
(l)
reason for your answer in
Q5(cxii)
marks)
(2 marks)
BEL 10103/BEX l0l03,tsEE
Q6
(a)
II
l3
Figure Q6(s) shows the RC circuit:
(D lfthe switch has been open lor a long time and is closed
and t(r).
at
F0, find
t,(t)
(7 marks)
(ii)
Ifthe switch has been closed for a long time and is opened
v, (r) and r(/).
at
F0, find
(6 marks)
(b)
Figure Q6(b) shows the spark coil ofan automobile ignition system, based on
this circuit:
(D
Calculate the value ofresistor, R, ifthe time needed for the coil to fully
charge is loms when ignition switch is closed.
(2 marks)
(ii)
Evaluate the steady state current when ignition switch is closed and draw
the cuftenl response.
(2 marks)
(iiD
lfthe switch takes lps to open, calculate the voltage developed
spark gap and the energy stored in the coil
across the
(3 marks)
Q7
(a)
Draw a source free series RLC circuit and derive the expression for damping
factor,o and resonance frequency,oo .
( l3 marks)
(b)
With the help ofdiagram, distinguish the response characteristics ofoverdamped, critically damped and underdamped for the circuit drawn in part Q7(a).
(3 marks)
(c)
For the circuit you have drawn in part Q7(a), given that -R=4O and C=0.IF. What
is the required inductor value, L, so that the RLC circuit behave asl
Overdampedresponse,
Critically damped response,
Underdamped
(D
(iD
(iii)
response.
14
.END OF QUESTION-
marks;
BEL 10103/BEX 10103/BEE
l
3
FINAL EXAMINATION
SEMESTER./SESSION :SEMll20lz/2013 PROGRAMME: BEB/ BEIV BEU/ BED/ BEC/ BEE
: ELECTRIC CIRCTJITS/ COURSE CODE : BEL t0t03/ BEX 10103/ BEE I I
ELECTRIC CIRCUIT I}IEORY
Il
COURSE
FIGURE O1(b)
100mA,
50 fuse
20v
500mW
FIGURE Ol(c)
BEL 10103/BEX 10103/BEE
lll3
FINAL EXAMINATION
SEMESTER/SESSION.SEM112012/2013 PROGRAMME: BEB/ BEIV BEU/ BED/
COURSE
I
ELECTRIC
CIRCUITS/
BEC/ BEE
COURSE CODE I BEL 10103/ BEX 10103/ BEE 1113
ELECTRIC CIRCUIT THEORY
FIGURE OI(d)
i"
12o
FIGURE O2(c)
BEL
l0l03aEx l0to3,tsEE
l
3
FINAL EXAMINATION
SEMESTER/SESSION
COURSE
rSEMy20lZ20l3
i ELECTRIC
CIRCUITS/
PROCRAMME: BEB/ BETY BEU/ BED/ BEC/ BEE
COURSECODE : BEL 10t03/ BEX 10t03/ BEE I I t3
ELECTRIC CIRCUIT TTIEORY
\
3.5 x
= 25om
FIGURE O3(a)
,-;\
,rr)
FIGURE O3(b)
l0'l
BEL lolo3,tsEx 10t03/BEE I I t3
FINAL EXAMINATION
SEMESTER/SESSION : SEM V2Ol2/2013
:ELECTRICCIRCUITS/
COURSE
PROGRAMME : BEB/ BEFV BEU/ BED/ BEC/ BEE
COURSE CODE : BEL t0103/ BEx t0103/ BEE I I l3
ELECTRIC CIRCUIT THEORY
500c)
FIGURE O4(a)
FIGURE O4(b)
BEL t0103/BEX 10103/BEE
1ll3
FINAL EXAMINATION
:
V2012?013
PROORAMME: BEB/ BEw BEU/ BED/ BEc/ BEE
ELECTRIC CIRCUITS/ COURSE CODE : BEL 10103/ BEX 10103/ BEE I I 13
ELECTzuC CIRCUIT THEORY
SEMESTER/SESSION rSEM
COURSE
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ra-..-..-..'--_,
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FIGURE O5(a)
150O
6u(t)V
*,I
FIGURE Os(c)
BEL 10103/BEX 10103/BEE l r t3
FINAL EXAMINATION
SEMESTER/SESSION
COURSE
rSEMV20lZ20l3 PROCRAMME: BEB/ BE}V B8U/ BED/ BEC/ BEE
CIRCUITS/ COURSE CODE : BEL 10103/ BEX 10103/ BEE I I l3
I ELECTRJC
ELECTRIC CIRCUIT THEORY
FIGURE O6(a)
&gap
FIGURE O6(b)
l0