Download 2013

Code No: R21023
R10
SET - 1
II B. Tech I Semester Supplementary Examinations Dec - 2013
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 about independent and dependent sources.
b) Two batteries are connected in parallel. The e.m.f and internal resistance of one are 110 V
and 6Ω respectively and the corresponding values for other are 130 V and 4Ω respectively.
A resistance of 20 Ω is connected across the parallel combination calculate: i) the value
and direction of the current in each battery
ii) the terminal voltage.
2. a) Employ nodal analysis technique to find v1 and i2 in the circuit shown in Figure 3.
b) Calculate the impedance of a series combination comprised of a 1 mF, 2 mF and 3 mF
capacitor if operated at a frequency of i) 1 Hz ii) 100 Hz.
3. a) Find the time-domain node voltages v1(t) and v2(t) in the circuit shown in Figure 4.
b) Compute the effective value of the periodic voltage waveform sketched in Figure 5.
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Code No: R21023
R10
SET - 1
4. a) A resistance R, L=0.02H and capacitance C connected series. When a voltage of
V cos(2000t 20 0 ) volts is applied to the series combination, the current flowing is
0
200
I5 2 cos(2000t - 65 )amps. Find R & C.
b) Find C which results in resonance in the circuit shown in Figure 6, when ω=5000rad/s.
5. a) Define the terms MMF, reluctance and flux in magnetic circuits.
b) Let is=(2 cos10t) A in the circuit shown in Figure 7. Find the total energy stored at t=0 when ‘ab’ is short- circuited.
6. Develop the graph of the network shown in Figure 8. Obtain the tie-set matrix by selecting tree.
7.
For the circuit shown in Figure 9, find the
a) Open circuit voltage Vab
b) Downward current in a short circuit between a and b.
c) Thevenin’s equivalent impedance Zab in parallel with the current source.
8. a) Verify Tellegen’s theorem for the circuit shown in Figure 10.
b) Verify the reciprocity theorem for the state reciprocity theorem and explain with suitable
example.
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Code No: R21023
R10
SET - 2
II B. Tech I Semester Supplementary Examinations Dec - 2013
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) A resistance of 20 Ω is connected in series with a condition of two resistances arranged in
parallel each of value 40 Ω. Determine the resistance R3 which should be shunted across the
parallel combination so that the total currents drown by the circuit is 1.5A with applied
voltage of 40 V.
b) Define node and branch. Count the number of nodes and branches for circuit shown Figure 2
2. a) Use mesh analysis to find V3 in the circuit shown in Figure 3.
b) For the circuit shown in Figure 4, compute the voltage across each current source.
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Code No: R21023
R10
SET - 2
3. a) Find the current i(t) in the circuit shown in Figure 5. Given that Vs (t)=40 sin3000t volts.
b) Compute average power absorbed by a 10Ω resistor whose voltage is given by the
waveform shown in Figure 6.
4.
a) Show that the resonant frequency ω0 of an RLC series circuit is the geometric mean of ω1and
ω2, the lower and upper half-power frequencies respectively.
b) A 10 H inductor, a 200 Ω resistor and a capacitor C are in parallel.
i) Find the impedance of the parallel combination at ω=100 rad/s. if C=20 µF.
ii) If the magnitude of the impedance is 125 Ω at ω=100 rad/s, find C.
5. a) The number of turns in two coupled coils are 600 and 1700, respectively. When a current of
6A flows in coil 2, the total flux in this coil is 0.8mWb, and the flux linking the first coil is
0.5mWb. Calculate L1, L2, M and K.
b) Explain the analogy between magnetic and electrical circuits.
6. a) The incidence matrix of a graph is given below in Table 1. Draw the direct graph.
b) What is meant by duality? Find dual of the network given in Figure 8.
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Code No: R21023
R10
SET - 2
7. a) Find the Thevenin’s equivalent circuit for the circuit shown in Figure 9.
b) State Millman’s theorem and give Millman’s equivalent for a circuit having ‘n’ number of
voltage sources in parallel.
8. a) Calculate the change in the current in the circuit shown in Figure 10, by compensation
theorem, when the reactance has changed to j35Ω.
b) State and explain Tellegen’s theorem.
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Code No: R21023
R10
SET - 3
II B. Tech I Semester Supplementary Examinations Dec - 2013
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 about ideal and non-ideal voltage and current sources with the help of V-I
characteristics.
b) Compute the power absorbed by each element of the circuit shown in Figure 2, and verify
that their sum is zero.
2.
a) Use mesh analysis to determine the three mesh currents in the circuit shown in Figure 3
b) Find the node voltages in the circuit shown in Figure 4.
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Code No: R21023
R10
SET - 3
3. a) Determine the equivalent impedance of the network shown in Figure 5, given an operating
frequency of 5 rad/s.
b) A resistance of 60 Ω, an inductance of 0.18H and a capacitance of 120 µf are connected in
parallel across a 100V, 50 Hz, supply. Calculate: i) current in each path ii) resultant
current iii) phase angle between the resultant current and the supply voltage iv) power
factor of the circuit.
4. A series circuit is constructed from two 5Ω resistors, four 100 µH inductors, and a 3.3 µF
capacitor.
a) Compute the resonant frequency of the circuit.
b) Calculate the quality factor of the circuit when operated at resonant frequency.
c) Determine the input impedance at
i) resonant frequency,
ii) 0.1 times the resonant frequency and iii)10 times the resonant
frequency.
5. a) Obtain an expression for coefficient of coupling in coupled circuits.
b) The two coupled inductors are connected as shown in Figure 7 with the following values:
L1=1H, L2 =3H and M=0.5H, i1=30sin 80t A and i2=30cos 80t A. Compute i) V1
ii) V2 .
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Code No: R21023
R10
SET - 3
6. a) Explain the concept of duality using a simple example.
b) Formulate the fundamental cut-set matrix for the graph shown in Figure 8.
7. a) Determine the Thevenin’s equivalent of the circuit shown in Figure 9.
b) Use superposition to find the value of Vx in the circuit shown in Figure 10.
8. a) In the circuit shown in Figure 11, the 3Ω resistance is changed to 5Ω. Determine the changes
in currents in
6Ω by using compensation theorem.
b) State and explain Superposition theorem with an example.
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Code No: R21023
R10
SET - 4
II B. Tech I Semester Supplementary Examinations Dec - 2013
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) Calculate VX in the above circuit Using method of Source Transformation Figure 1.
b) Distinguish between i) Unilateral and bilateral
iii) Active and passive elements
ii) Lumped and distributive elements
2. a) Find the source current in the resistive network shown in Figure 3, by using Y- Δ
transformation.
b) Find Io in the circuit shown in Figure 4, using concept of source transformation.
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Code No: R21023
R10
SET - 4
3. a) For the circuit shown in Figure 5, find the complex power absorbed by the load. Then
determine the apparent power, the average power, and the reactive power delivered to the
load.
b) Determine the effective value of the periodic signal given in the Figure 6.
4. a) Draw the current locus for a series R-L circuit.
b) A coil of 2.2Ω resistance and 0.01H is connected in series with a capacitor across 220V
mains. Find the value of capacitance such that the maximum current flows in the circuit at
a frequency of 100Hz. Also, find the current and voltage across the capacitor.
5. a) Explain the dot convention in coupled circuits.
b) Two coils with a coefficient of coupling of 0.6 between them, are connected in series so as
to magnetize i) in one combination in the same direction and ii) in another combination in
the opposite direction. The corresponding values of equivalent inductance are 1.8H and
0.8H respectively. Find the self inductance of the two coils and the mutual inductance
between them.
6. Draw the oriented graph of network shown in Figure 7. Write the incidence matrix.
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R10
Code No: R21023
SET - 4
7. a) If any value whatsoever may be selected for RL in the circuit shown in Figure 8, what is the
maximum power that could be dissipated in RL?
b) Find the Thevenin’s equivalent circuit for the circuit shown below Figure 9.
8. a) State and verify reciprocity theory using a simple example.
b) Find the current i for the circuit shown in Figure 10.
3Ω
+
- 24 V
2Ω
+ 3i
-
7A
Figure 10
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