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Beg.I{o-
:
Question
Paper
Code
: 97063
B.
tr. /B.
Te
ch.
D E GREE
HLqNIILATIO
N,
NO\IEII,IBER/D
E CtrVIB tr
R
20
L 4.
Electronics
and
Com munication
Engineering
EE
620I
-
CIRCUIT
THEORY
(Common
to
Electrical
and
Electronics
Engineering, Electronics
and
I nstrument
ation
Enginee
ring,
Instruraentation
Enginee rin
g,
Biomedical
Engineering
and
h[edical
Electronics
Engineering)
.
Gegulation
2013)
Time :
Three
hours
Maxirnum
: 100 marks
Answer
ALL
questions-
PARTA-(10
x 2=?$
marks)
1. An
electrical
appliane
ooosumes
1.2 kwh
in
30
mins
at
L20
V. What is
the
current
drarvn
bY
tle
aPPliance?
2.
Calculate
the
equivalent
resistance
between
the terminals
{o"
and
"b",
in
Fig.
1.
TIio
1
r rli'
I
Calculate
the
value
of
f*
for the circuit
shown
in Fig. 2,
a
3.
tlv
Fig.2
Rr-
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4.
5.
State
maximum
power
transfer
theorem
for
DC
networks.
Calculate
the
total
inductance
of the
circuit,
if
the coefficient
of coupling
(/e)
betleen
the two
coils
is
0.6, as
ihown
in
Fig.
B.
33mH
h't
rnH
i
:
Fig.S
Definequa1ityfactorofaseriesresonantcircuit.
A
coil of resistance
2.2
O
and
an
inductance
0.01
H is
connected
in
series
with
a
capacitor
across 220
V
mains. Find,
the.value
of
capacitance
such that
maximum
current flows
in
the circuit
at
a frequency
of
190
Hz. Also
find
the
maximum current.
A 50
pF
capacitor
is
discharged
through
a 100
kO resistor.
If
the capacitor
is
initially
charged
to 400
V, determine
the
initial
energy.
Write
the'equations
for
the
phasor
difference
between
the
potentials
of
the
delta
connected
networks.
Three coils,
each
having
a
resistance
of
20
Q
and an
inductive
reactance
of
15
c)
are
connected
in
btar to a
400
v,
B-phase,
and
5o Hz
supply.
Calculate
(a)the1inecurrent,ft)powerfactor,and(cJpowersupplied..
PARTB-(5xlG=80marks)
\u
^
rv
_
9v llralAt
11,
(a) (i)
Using
node
analysis,
find
the
node
voltages
and
the
currents
.
through
all the
resistors
for
the
circuit"shown
in Fig.
4.
(12)
Fig.4
2
6.
7.
8.
10.
l9l
^
2o
-sa
IJL
15A
97063
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(ir)
'Fiod.
the
equivaleut
reeistance
betmeen
the
erminals
'o'
and
'b'
for
the
network
sb*ain
Flg. 5.
(4)
.
F'€-5
Or
.
::
(b)
For
the
circuit
shmn
in
FIg:
6, frnd
the
(i)
currents
in
diffrcrent
branches,
(ii)
current
supplied
hry
tre
battery,
(iii)
potential
differene
between
ierrninals
A
andB-
(16)
(a)
Find
the
current
d,
tlmugh
the
20
O
resistor shown
in
Frg.
7
using
Thevenin's
theuem-
(16)
L2.
Fig.'7
Or
3
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circuit
shown
iu Fie.
8.
_
:.$
.t_
*,
.r
:.*,
.
,9,
(b):
Find the
current throughffiI
resistor
using superpbsition
theorem,
in
the
"s:;
.F :i
6+}{i;
ii
Fig.8
5
Kit-
+n
(16)
(16)
(a).
'
Impedance
Z,
and
Z, areytaxallel
and
this combination
is in
series
with
,
an impedance
:Zr,
connecte{.to
a
100 Vi 50,H2
ac
suppl5r-
Z,
=
(5
-
ix)et,
Z)=15+
j0)O
,
?t=$.25+1T--25)Q.
Determine
the
value of
capacitance
'
such
that
the total currentlOf
the
ci.reuit
will be
in
phase
with the total
voltage.
Find
the circuit
cu*at
and
power.
'
t'Or
G)
,
,
The
switch
in the circuit
shOryn
in
Fig. 9 is
moved
from
position
1 to
2 at
f
=
0.
Find.
the
expression
{or voltage
across
resistahce
and
capacitor,
eRergy
in
the
capacitor
for
l'>0-
toov
Fig.9
4
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L4.
(a)
(i)
For
a
magletiflly
coupled ctcqit, derive
the
expression.for
mutual
ms
of, 'rrd
I?-
(6)
.
(ii)
For
the
corrpled
cfu,cuit shownin Fig-
10, find the value of.
V, so that
15.
(a)
Shovr
that
three
phase power
can be
measured
by
two wattmeters.
Draw
the
phasor
diagrams.
Derive
an
expression
for
power
factor
interms
of
Fig. 10
:
Or
(b)
With
neat
illustration,
describe
thre
parallel
resonant
equivalent
parallel
network
for a
series
RL
combination.
.
unity
power
fact.r;fi,
fo.
(b)
(,
circuit
and
the
Also derive the
(16)
(16)
,
(8)
97063
wattme6r
ps2dings.
Or
A 400
V
(tine
to line)
is
applied.
to three star
connected
identical
impedances
each
consisting
of
.a
4 O
resistance
in series
with
3
O
inductive
reactance.
Find
(1)
line
current
and
(2)
total
power
6Jl-
2"JL
supplied.
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