circuit theory nov-dec 2014

8/9/2019 Circuit Theory NOV-DeC 2014

1/12

1. An electrical appliances consumes 1.2KWh in 30 mins

at 120V.What is the current drawn by the appliances?

(ANNA N!V N"V#$%& 201'()e* 2013

2. &alculate the e+ui,alent resistance between the

terminals -a -and -b /i*.1(ANNA N!V N"V#$%& 201'

()e* 2013

3. &alculate the ,alue o !N or the circuit shown in /i*.2.

(ANNA N!V N"V#$%& 201'()e* 2013

'. tate maimum power transer theorem or $&

networs. (ANNA N!V N"V#$%& 201'()e* 2013

4. &alculate the total inductance o the circuit5 i the

coe6cient o couplin* ( between the two coils is

0.75as shown in /i*.3. (ANNA N!V N"V#$%& 201'()e*

2013

7. $e8ne the +uality actor o a series resonant circuit.

(ANNA N!V N"V#$%& 201'()e* 2013

9. A coil resistance 2.2: and an inductance 0.01; isconnected in series with a capacitor across 220V


2/12

mains. /ind the ,alue o capacitance such that

maimum current .Also 8nd the maimum current. (ANNA N!V

N"V#$%& 201'()e* 2013

. A 40@/ capacitor is dischar*ed throu*h a 100K:

resistor. ! the capacitor is initially char*ed to

'00V5determine the initial ener*y. (ANNA N!V N"V#

$%& 201'()e* 2013

=. Write the e+uations or the phasor dierence between

potentials o the delta#connected networs. (ANNA

N!V N"V#$%& 201'()e* 2013

10. Bhree coils5 each ha,in* a resistance o 20: and

an inducti,e reactance o 14: are connected in star toa '00V5 3#phase5 and 40;> supply. &alculate (a the line

current5 (b power actor5 and (c power supplied.

(ANNA N!V N"V#$%& 201'()e* 2013

11. (a (i sin* node analysis5 8nd the node ,olta*es and

the currents throu*h all resistors or the circuit shown in

/i*.'. (12 (ANNA N!V N"V#$%& 201'()e* 2013

(ii /ind the e+ui,alent resistance between the terminals CaD

and CbDor the networ shown in /i*.4. (' (ANNA N!V N"V#

$%& 201'()e* 2013


3/12

(b/or the circuit shown in /i*.7.8nd the (i currents in

dierent branches5 (ii current supplied by the battery5 (iii

potential dierence between terminals A and E (17 (ANNA

N!V N"V#$%& 201'()e* 2013

12. (a /ind the current !5 throu*h the 20: resistor shown in

/i*.9. usin* Bhe,eninDs theorem (17 (ANNA N!V N"V#$%&

201'()e* 2013

(b/ind the current throu*h 4: resistor usin* superposition

theorem5 in the circuit shown in /i*.. (17 (ANNA N!V N"V#


4/12

$%& 201'()e* 2013

13. (a !mpedance F1 and F2 are parallel and this

combination is in series wit an impedance F35 connected to a

100V5 40;> ac supply. F1G(4#HIc :5 F2G(4JH0 :5

F3G(7.24JH1.24$etermine the ,alue o capacitance such

that the current o the circuit will be in phase with the total,olta*e. /ind the circuit current power. (17 (ANNA N!V

N"V#$%& 201'()e* 2013

(b Bhe switch in the circuit shown in /i*.= is mo,ed rom

position 1 to 2 a tG0./ind the epression or ,olta*es across

resistance and capacitor5 ener*y in the capacitor or t0.


5/12

(17 (ANNA N!V N"V#$%& 201'()e* 2013

1'(a(i /or a ma*netically coupled circuit5 deri,e theepression or mutual inductance (m in terms L1 and L2. (7

(ANNA N!V N"V#$%& 201'()e* 2013

(ii /or the coupled circuit shown in /i*.10. /ind the ,alue o

V2 so that the current !1G0. (10 (ANNA N!V N"V#$%& 201'


6/12

()e* 2013

(bWith neat illustration5 describe the parallel resonant

circuit and the e+ui,alent parallel networ or a series )L

combination. Also deri,e the unity power actor5 fp (17

(ANNA N!V N"V#$%& 201'()e* 2013

14. (a how that three#phase power can be measured by

two wattmeters. $raw the phasor dia*rams. $eri,e an

epression or power actor interms o wattmeter readin*s.

(17 (ANNA N!V N"V#$%& 201'()e* 2013

(b(iA '00V (line to line is applied to three star connected

identical impedances each consistin* o a ': resistance in

series with 3: inducti,e reactance. /ind the (1 line current

(2 total power supplied ( (ANNA N!V N"V#$%& 201'()e*2013

(ii Bhree star#connected impedances F1G(20JH39.9 :5 per

phase are in parallel wit three delta#connected impedances

F2G(30#H14=.3 : per phase. Bhe line ,olta*e is 3= ,olts.

/ind the line current5 power actor5 power and reacti,e ,olt#

ampere taen by the combination. ( (ANNA N!V N"V#$%&

201'()e* 2013


7/12

nit 11. An electrical appliances consumes 1.2KWh in 30 mins

at 120V.What is the current drawn by the appliances?

(ANNA N!V N"V#$%& 201'()e* 2013

2. &alculate the e+ui,alent resistance between theterminals -a -and -b /i*.1(ANNA N!V N"V#$%& 201'

()e* 2013

11. (a (i sin* node analysis5 8nd the node ,olta*es and

the currents throu*h all resistors or the circuit shown in

/i*.'. (12 (ANNA N!V N"V#$%& 201'()e* 2013

(ii /ind the e+ui,alent resistance between the terminals CaD

and CbDor the networ shown in /i*.4. (' (ANNA N!V N"V#

$%& 201'()e* 2013


8/12

(b/or the circuit shown in /i*.7.8nd the (i currents in

dierent branches5 (ii current supplied by the battery5 (iii

potential dierence between terminals A and E (17 (ANNA

N!V N"V#$%& 201'()e* 2013

nit 21. &alculate the ,alue o !N or the circuit shown in /i*.2.

(ANNA N!V N"V#$%& 201'()e* 2013

2. tate maimum power transer theorem or $&

networs. (ANNA N!V N"V#$%& 201'()e* 2013


9/12

12. (a /ind the current !5 throu*h the 20: resistor shown in

/i*.9. usin* Bhe,eninDs theorem (17 (ANNA N!V N"V#$%&

201'()e* 2013

(b/ind the current throu*h 4: resistor usin* superposition

theorem5 in the circuit shown in /i*.. (17 (ANNA N!V N"V#

$%& 201'()e* 2013

nit 31. &alculate the total inductance o the circuit5 i the

coe6cient o couplin* ( between the two coils is

0.75as shown in /i*.3. (ANNA N!V N"V#$%& 201'()e*

2013


10/12

2. $e8ne the +uality actor o a series resonant circuit.

(ANNA N!V N"V#$%& 201'()e* 2013

13. (a !mpedance F1 and F2 are parallel and this

combination is in series wit an impedance F35 connected to a

100V5 40;> ac supply. F1G(4#HIc :5 F2G(4JH0 :5

F3G(7.24JH1.24$etermine the ,alue o capacitance suchthat the current o the circuit will be in phase with the total

,olta*e. /ind the circuit current power. (17 (ANNA N!V

N"V#$%& 201'()e* 2013

(b Bhe switch in the circuit shown in /i*.= is mo,ed rom

position 1 to 2 a tG0./ind the epression or ,olta*es across

resistance and capacitor5 ener*y in the capacitor or t0.

(17 (ANNA N!V N"V#$%& 201'()e* 2013


11/12

nit '1. A coil resistance 2.2: and an inductance 0.01; is

connected in series with a capacitor across 220V

mains. /ind the ,alue o capacitance such that

maimum current .Also 8nd the maimum current. (ANNA N!V

N"V#$%& 201'()e* 2013

2. A 40@/ capacitor is dischar*ed throu*h a 100K:

resistor. ! the capacitor is initially char*ed to

'00V5determine the initial ener*y. (ANNA N!V N"V#

$%& 201'()e* 2013

1'(a(i /or a ma*netically coupled circuit5 deri,e the

epression or mutual inductance (m in terms L1 and L2. (7

(ANNA N!V N"V#$%& 201'()e* 2013

(ii /or the coupled circuit shown in /i*.10. /ind the ,alue o

V2 so that the current !1G0. (10 (ANNA N!V N"V#$%& 201'

()e* 2013

(bWith neat illustration5 describe the parallel resonant

circuit and the e+ui,alent parallel networ or a series )L

combination. Also deri,e the unity power actor5 fp (17 (ANNA N!V N"V#$%& 201'()e* 2013


12/12

nit 41. Write the e+uations or the phasor dierence between

potentials o the delta#connected networs. (ANNA

N!V N"V#$%& 201'()e* 2013

2. Bhree coils5 each ha,in* a resistance o 20: and an

inducti,e reactance o 14: are connected in star to a

'00V5 3#phase5 and 40;> supply. &alculate (a the line

current5 (b power actor5 and (c power supplied.

(ANNA N!V N"V#$%& 201'()e* 2013

14. (a how that three#phase power can be measured by

two wattmeters. $raw the phasor dia*rams. $eri,e an

epression or power actor interms o wattmeter readin*s.

(17 (ANNA N!V N"V#$%& 201'()e* 2013

(b(iA '00V (line to line is applied to three star connected

identical impedances each consistin* o a ': resistance in

series with 3: inducti,e reactance. /ind the (1 line current

(2 total power supplied ( (ANNA N!V N"V#$%& 201'()e*

2013

(ii Bhree star#connected impedances F1G(20JH39.9 :5 per

phase are in parallel wit three delta#connected impedancesF2G(30#H14=.3 : per phase. Bhe line ,olta*e is 3= ,olts.

/ind the line current5 power actor5 power and reacti,e ,olt#

ampere taen by the combination. ( (ANNA N!V N"V#$%&

201'()e* 2013

circuit theory nov-dec 2014

Documents