Download JNTUA B.Tech 1-2 R15 2019 Dec Supple 15A02201 Electrical Circuits I Question Paper

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ELECTRICAL CIRCUITS ? I
(Electrical and Electronics Engineering)
Time: 3 hours Max. Marks: 70
PART ? A
(Compulsory Question)

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*****
1 Answer the following: (10 X 02 = 20 Marks)
(a) Two capacitors having capacitances of 10 ? and 15? respectively are connected in series across
a 200 V d.c supply. Calculate: (i) Voltage across each capacitor. (ii) Equivalent capacitance of the

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circuit.
(b) State the faradays first law of electromagnetic induction.
(c) Two impedances (5+j7)? and (10-j7)? are connected in series across a 200 V supply. Calculate the
current and power factor.
(d) Define power factor.

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(e) A series RLC circuit with L = 1 mH and C = 1000 pF is connected across a sinusoidal source of 20 V
with variable frequency. Compute the resonant frequency.
(f) In a series RLC circuit, if the value of L and C are 100mH and 0.1 ? . Determine the value of R to
give critical damping.
(g) What is the condition for maximum power transfer in DC circuits?

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(h) List the applications of Thevenin?s theorem.
(i) A two port network is characterized by V
1
= 10 I
1

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+ 5 I
2
and V
2
= 5 I

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1
+ 12 I
2
. Find the transmission
parameters A and C.

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(j) The impedance parameters of a two port network are Z
11
= 6 ?; Z
22
= 4 ?; Z

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12
= 3?; Z
21
= 3 ?.
Compute the Y parameters of network.

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PART ? B
(Answer all five units, 5 X 10 = 50 Marks)

UNIT ? I

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2 (a) Define Faraday?s laws of electromagnetic induction.
(b) An iron ring of mean length 40 cm has an air gap of 2 mm and a winding of 300 turns. If the
permeability of the iron core is 300, when a current of 1A flows through the coil, find the flux density.
OR

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3 Determine the equivalent resistance of the circuit shown below.


Contd. in page 2

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Page 1 of 2


R15

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? 1
= 6 ?
? 2
= 8 ?
? 3

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= 4 ?
? 4
= 8 ?
? 5
= 4 ?

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? 6
= 6 ?
? 7
= 8 ?
? 8

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= 10 ?
? 9
= 6 ?
? 1 0
= 2 ?

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? ?

?
?
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Code: 15A02201


B.Tech I Year II Semester (R15) Supplementary Examinations December 2019

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ELECTRICAL CIRCUITS ? I
(Electrical and Electronics Engineering)
Time: 3 hours Max. Marks: 70
PART ? A
(Compulsory Question)

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*****
1 Answer the following: (10 X 02 = 20 Marks)
(a) Two capacitors having capacitances of 10 ? and 15? respectively are connected in series across
a 200 V d.c supply. Calculate: (i) Voltage across each capacitor. (ii) Equivalent capacitance of the

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circuit.
(b) State the faradays first law of electromagnetic induction.
(c) Two impedances (5+j7)? and (10-j7)? are connected in series across a 200 V supply. Calculate the
current and power factor.
(d) Define power factor.

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(e) A series RLC circuit with L = 1 mH and C = 1000 pF is connected across a sinusoidal source of 20 V
with variable frequency. Compute the resonant frequency.
(f) In a series RLC circuit, if the value of L and C are 100mH and 0.1 ? . Determine the value of R to
give critical damping.
(g) What is the condition for maximum power transfer in DC circuits?

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(h) List the applications of Thevenin?s theorem.
(i) A two port network is characterized by V
1
= 10 I
1

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+ 5 I
2
and V
2
= 5 I

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1
+ 12 I
2
. Find the transmission
parameters A and C.

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(j) The impedance parameters of a two port network are Z
11
= 6 ?; Z
22
= 4 ?; Z

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12
= 3?; Z
21
= 3 ?.
Compute the Y parameters of network.

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PART ? B
(Answer all five units, 5 X 10 = 50 Marks)

UNIT ? I

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2 (a) Define Faraday?s laws of electromagnetic induction.
(b) An iron ring of mean length 40 cm has an air gap of 2 mm and a winding of 300 turns. If the
permeability of the iron core is 300, when a current of 1A flows through the coil, find the flux density.
OR

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3 Determine the equivalent resistance of the circuit shown below.


Contd. in page 2

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Page 1 of 2


R15

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? 1
= 6 ?
? 2
= 8 ?
? 3

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= 4 ?
? 4
= 8 ?
? 5
= 4 ?

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? 6
= 6 ?
? 7
= 8 ?
? 8

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= 10 ?
? 9
= 6 ?
? 1 0
= 2 ?

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? ?

?
?

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Code: 15A02201

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UNIT ? II

4 A 10? resistor and a 20 mH inductor are connected in series across a 250 V, 60 Hz supply. Find:
(i) Impedance of the circuit.
(ii) Voltage across the resistor.

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(iii) Voltage across the inductor.
(iv) Active power.
(v) Reactive power.
OR
5 A coil of power factor 0.6 is in series with a 100 ? capacitor. When connected to a 50 Hz supply, the

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potential drop across the coil is equal to the potential drop across the capacitor. Find the resistance
and inductance of the coil.

UNIT ? III

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6 For the circuit shown in below. Determine the frequency at which the circuit resonates. Also find the
quality factor, voltage across the inductor and capacitor at resonance.

OR
7 (a) Derive the Quality factor of the parallel RLC circuit at Resonance.

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(b) Derive the Quality factor of the series RLC circuit at Resonance.

UNIT ? IV

8 State Thevenins theorem. Write the steps to be followed in applying Thevenins theorem.

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OR
9 Verify the reciprocity theorem in the circuit shown in figure below and also calculate the transfer
resistance.

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UNIT ? V

10 Derive the relation between transmission parameters and admittance parameters.
OR
11 For the h-parameter for the network shown below.

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*****
Page 2 of 2

? = 12 ? ? = 0.15 ? ? = 100 ?

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? ? ? ? ? ?
I
? ? = 100 ?
R15
5 ?

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5 ?
2
2
I
1

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I

1
? 1
? 2

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