eee - circuit theory - nov-dec - 2014 - reg.13

8/9/2019 Eee - Circuit Theory - Nov-Dec - 2014 - Reg.13

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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-


2/6

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


3/6

(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

97063


4/6

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

97063


5/6

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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