Code No: R21023

II B.Tech I Semester, Regular Examinations, November - 2011

ELECTRICAL CIRCUIT ANALYSIS - I

(Electrical and Electronics Engineering)

Time: 3 hours Max Marks: 75

Answer any FIVE Questions

All Questions carry equal marks

1. a) What is the different between an ideal source and a practical source? Draw the relevant

characteristics of the above sources. (6M+4M+5M)

b) Explain the source transformation used in electrical network with suitable example.

c) A capacitor of 1F is supplied with voltage waveform shown in figure (1).Obtain the current

and energy waveforms in the capacitor.

2. a) State and explain kirchoff’s laws. (5M+10M)

b) Find Req between terminals x and y as shown in figure (2). All resistor values are in �.

3. a) Define the following i) RMS value, ii) Average value and iii) Form factor of an alternating

quantity. (6M)

b) The voltage of a circuit is v =200sin (ωt+ 30 º) and the current is i=50sin (ωt+60º). Calculate

i) the average power, reactive volt amperes and apparent power and ii) Find the circuit elements

if ω =100� rad/sec. (9M)

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4. a) Explain the salient features of series resonant circuit when compared to parallel resonant

circuit. (6M)

b) A series RLC circuit has R=10ohm, L= 0.5H and C= 40�F. The applied voltage is 100V.

Find i) resonant frequency, ii) Quality factor of a coil, iii) Upper and lower half power

frequencies, iv) Band width, v) current at resonance, vi) current at half power points and

vii) Voltage across inductance at resonance. (9M)

5. a) Define i) MMF, ii) flux and iii) reluctance in connected with magnetic circuit. (6M)

b) An iron ring of circular section of 2cm diameter has a mean diameter of 40cm and is wound

with 200 turns of wire. An air gap of 0.1cm is cut across the ring. The useful flux in the air gap

is to be 2×10-4

wb. Calculate the current required in the wire. Assume the relative permeability

of iron to be 900. (9M)

6. a) Explain the following

i) connected graph, ii) planar graph, iii) oriented graph and vi) sub graph. (6M)

b) Obtain the basic Tie set matrix for the graph shown in figure (3), taking the tree consisting of

branches 2, 4, 5. Write down the voltage and current expressions. (9M)

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7. a) State and explain Maximum power transfer theorem. (6M)

b) Determine the current through 1ohm resistor for the circuit shown in figure (4) by using

Thevenin’s theorem. (9M)

8. a) State and explain Reciprocity theorem. (6M)

b) Determine the current in 10 ohm resistor across AB of the network shown in figure (5) by

using superposition theorem. (9M)

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Code No: R21023

II B.Tech I Semester, Regular Examinations, November - 2011

ELECTRICAL CIRCUIT ANALYSIS - I

(Electrical and Electronics Engineering)

Time: 3 hours Max Marks: 75

Answer any FIVE Questions

All Questions carry equal marks

1. a) Explain the volt-ampere relationships of R, L and C elements. (6M)

b) A voltage given by v = 6t volts is connected across a 25 ohm resistor. Determine the energy

dissipated by the resistor during the interval 0 � t � 5sec. (4M)

c) What are dependent sources? What are the various types of dependent sources? (5M)

2. a) Calculate the currents in each branch for the network shown in figure (1) by using Nodal

analysis. (7M)

b) Find the equivalent resistance between the terminals x and y in figure (2). All resistor values

are in ohms. (8M)

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3. a) Define the following i) impedance, ii) reactance, iii) phase angle difference and

iv) Power factor. (4M)

b) What is the J- operator? Explain the significance of J-operator? (4M)

c) The Admittance of a circuit is (0.05-j0.08) mhos. Find the values of resistance and inductive

reactance of the circuit if they are connected i) in parallel and ii) in series.

(7M)

4. a) Draw the current, impedance and admittance loci for an RL series circuit having constant

resistance but variable inductive reactance. (7M)

b) Obtain the resonant frequency for a circuit consisting of R-L elements connected in parallel

to capacitance. Also obtain expression for Q- factor in terms of R, L and C. (8M)

5. a) Explain dot convention used in magnetically coupled coil. (5M)

b) Explain i) self inductance and ii) mutual inductance. (4M)

c) A coil of 150 turns is linked with a flux of 0.01wb when carrying a current of 10A; calculate

the inductance of the coil. If this current is uniformly reversed in 0.01sec, calculate the induced

emf? (6M)

6. a) Explain different properties of a tree of a given graph. (6M)

b) Find the fundamental cut set matrix of the graph by taking 1,2,4,5 as the branches of a tree

for the following graph shown in figure (3). (9M)

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7. a) State and explain Millman’s theorem. (6M)

b) Determine the current I in the network using Thevenin’s theorem. Refer figure (4).

(9M)

8. a) State and explain Tellegen’s theorem. (6M)

b) Verify Reciprocity theorem for the network shown in figure (5). (6M)

c) State the limitation of the superposition theorem? (3M)

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Code No: R21023

II B.Tech I Semester, Regular Examinations, November - 2011

ELECTRICAL CIRCUIT ANALYSIS - I

(Electrical and Electronics Engineering)

Time: 3 hours Max Marks: 75

Answer any FIVE Questions

All Questions carry equal marks

1. a) Explain the difference between active elements and passive elements with suitable

examples. (4M+4M+7M)

b) Explain the source transformation used in electrical networks with relevant examples.

c) A current wave form shown in figure (1) is applied to a capacitor of value 2µF. Find the

voltage wave form across it?

2. a) Determine the current in 5ohm resistor for the circuit shown in figure(2) by using super

node analysis. (8M)

b) Find the voltage to be applied across AB in order to drive a current of 5A into the circuit by

using star-delta transformation. Refer figure (3) (7M)

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3. a) Derive the expression for power in a single phase AC circuit contains R-L elements in series.

(5M+5M+5M)

b) A supply of 400 V, 50Hz is applied to a series R-C circuit. Find the value of C if the power

absorbed by the resistor to be 500W at 150V. What is the energy stored in a capacitor?

c) An RLC series circuit has R= 4ohms, XL=19.5ohms and XC=12ohms.Calculate the power

factor of the circuit.

4. a) Draw the current, impedance and admittance loci for a RC series circuit having constant

resistance but variable capacitance. (6M+9M)

b) What values of L and C should be used in a tank circuit, to obtain resonance frequency of 5

kHz. The band width must be 500Hz. The winding resistance of the coil is 10ohm.

5. a) Explain the Faraday’s laws of electro-magnetic induction? (6M)

b) Derive the expression for coefficient of coupling between two magnetically coupled coils in

terms of their self and mutual inductance. (6M)

c) Two coupled coils of L1 = 0.8H and L2 = 0.2H have a coupling coefficient of K = 0.9. Find

the mutual inductance M and the turn’s ratio N1/N2. (3M)

6. a) Define the following i) node pair, ii) rank, iii) Nullity, iv) loop and v) path in connection with

network topology. (5M)

b) How do you obtain incidence matrix for the graph shown in figure (4). Also, obtain the

relationship between node and branch voltages. (10M)

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7. a) State and explain Norton’s theorem. (6M)

b) Determine the value of RL for which power transfer is maximum for the network shown in

figure(5). Find also, the maximum power? (10M)

8. a) State and explain superposition theorem. (6M)

b) In the network shown in figure (6), 5ohm resistor is changed to 8ohms. Determine the

resulting change in current through (3+j4) impedance. Use compensation theorem. (10M)

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Code No: R21023

II B.Tech I Semester, Regular Examinations, November - 2011

ELECTRICAL CIRCUIT ANALYSIS - I

(Electrical and Electronics Engineering)

Time: 3 hours Max Marks: 75

Answer any FIVE Questions

All Questions carry equal marks

1. a) Explain i) practical voltage source and ii) ideal voltage source

(4M)

b) The voltage wave form shown in figure (1) is applied across Capacitor, C=1F. Draw the

current wave form across it. (8M)

c) State the advantages of source transformation (3M)

2. a) Find the input resistance of the circuit shown in figure (2).

b) Use mesh analysis to find the current Ia in figure (3) (8M+7M)

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3. a) What is a Form Factor of an alternating quantity? Explain its significance? (5M)

b) An inductive coil takes 10 Amperes and dissipates 1000watts when connected to a supply of

250 V, 50Hz. Calculate i) the impedance, ii) the effective resistance , iii) reactance,

iv) the inductance and v) power factor. Also draw the vector diagram. (10M)

4. a) In a series RLC circuit, R=1k �, L=120 mH and C =12 pF. If a voltage of 200volts is applied

across the combination, determine i) resonance frequency, ii) Q-factor , iii) half power

frequencies, iv) Band width and v) voltage across the inductance and the capacitance. (10M)

b) Obtain the impedance locus of parallel connected elements (Take R and L elements) (5M)

5. a) Explain the following terms: (6M)

i) Magnetic circuit, ii) permeability, iii) Magneto Motive Force and iv) Reluctance

b) A Cast steel ring has a circular cross section 3 cm in diameter and a mean circumference of

80 cm. The ring is uniformly wound with 600 turns. i) Find the current required to produce a

flux of 0.5 milli Weber in the ring ii) If a saw cut 2mm wide is made in the ring, find

approximately the flux produced by the current found in i) (9M)

6. a) How do you say the duality exists between Thevenin’s theorem and Norton’s theorem? (5M)

b) Obtain the incidence matrix for the graph shown in figure (4). Write the KCL and KVL

equations for the graph. Take node (4) as reference node. (10M)

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7. a) State and explain Norton’s theorem (6M)

b) Obtain VAB by Millman’s theorem and verify our result by Thevenin’s theorem.

Refer figure (5). (9M)

8. a) State and explain Superposition theorem (6M+9M)

b) Using Superposition theorem, Calculate the current is in the network shown in figure (6)

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