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Code No: R05010401 Set No. 1

I B.Tech Semester Supplimentary Examinations, June 2009 NETWORK ANALYSIS

( Common to Electronics & Communication Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering, Electronics &

Telematics and Electronics & Computer Engineering) Time: 3 hours Max Marks: 80

Answer any FIVE Questions All Questions carry equal marks

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1. (a) The following current wave form i(t) is passed through a series R-L circuit with R =2 Ω and L =2 mH. Find the Voltage across each element and sketch the same. (Figure 1a)

Figure 1a

(b) Using nodal analysis, determine the Power supplied by 8V Voltage source. (Figure 1b)

Figure 1b

(c) Write the Tieset matrix for the graph shown in Figure 1c, taking the tree consisting of branches 2,3,4. [6+6+4]

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Code No: R05010401 Set No. 1

Figure 1c

2. (a) Explain the Dot convention for mutually coupled coils.

(b) Two coils A & B having 100 and 250 turns respectively are wound side by side on a magnetic material having a c.s.area of 10 cm2 and a mean length of 150 cms The permeability of the material is 500. Determine the self-inductance of the two coils A & B and mutual inductance between them. If the current in coil A changes from zero to 2A in 0.01 seconds, find the Emf induced in the coil B.

(c) Derive the relation between the flux density B, and magnetizing force H. Sketch the general shape of B-H curve for both magnetic and nonmagnetic materials.

[4+8+4]

3. (a) the circuit (Figure 3a) shown, the switch is changes from position 1 to 2 at t=0. Determine the initial conditions i , di/dt , d2i/ dt2at t=0+

Figure 3a

(b) In the parallel resonant circuit, determine the resonance frequency, dynamic resistance and Band width for the circuit (Figure 3b) shown.

Figure 3b

(c) When an voltage of 220V A.C supply connected across the AB terminals, the

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Code No: R05010401 Set No. 1

total power input is 3.25kw and the current is 20Amps. Find the current through Z3.(Figure 3) [6+6+4]

Figure 3

4. (a) Find the Laplace Transform of single pulse shown in Figure 4a.

Figure 4a

(b) Define RMS value, Average value, Form factor of an alternating quantity. Also state the relationship between them.

(c) Find the RMS value of the voltage wave whose equation is v(t)=10+200 Sin(wt-30o)+100Cos3wt-50 Sin(5wt+600). [8+4+4]

5. (a) A heating element pure resistive rated for 450 watts, 110 V is to be worked from 220V, 50Hz main supply by connecting a series inductor. Calculate the value of the inductance needed?

(b) A load consumes 100 watts at 0.8 p.f lagging. If the load voltage and current phasors are expressed as follows, evaluate A and B:

V=(25+jA) volts I=(B+j1) Amps. [8+8]

6. (a) Find the y-parameters of the network shown in Figure 6a and there by obtain z-parameters.

Figure 6a

(b) Obtain the expressions to get symmetry and reciprocity of a given network in terms of g-parameters. [12+4]

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Code No: R05010401 Set No. 1

7. Derive the expressions for attenuation constant, phase constant, cut-off frequency and characteristic impedance of a symmetrical Π section. [16]

8. (a) What is constant k-filter? What is the difference between constant k-filter and m-derived filter? What are the limitations of constant K-filter?

(b) Find the circuit parameters of a constant k-band pass filter having a pass band from 500 Hz and a characteristic resistance of 100Ω. [8+8]

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Code No: R05010401 Set No. 2

I B.Tech Semester Supplimentary Examinations, June 2009 NETWORK ANALYSIS

( Common to Electronics & Communication Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering, Electronics &

Telematics and Electronics & Computer Engineering) Time: 3 hours Max Marks: 80

Answer any FIVE Questions All Questions carry equal marks

⋆ ⋆ ⋆ ⋆ ⋆

1. (a) Define Graph and Tree of a Network.

(b) Determine the Current through 3 ohms resistor using Nodal method of Analy- sis for Figure 1b.

Figure 1b

(c) Draw the graph of the Network shown in Figure 1 and obtain the basic cutset schedule. Choosing one possible tree. [2+8+6]

Figure 1

2. (a) Explain the concept of impedance transformation with an ideal transformer.

(b) Write down the loop equation for the coupled network shown in Figure 2b.

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Code No: R05010401 Set No. 2

Figure 2b

(c) Two coils are wound side by side on a nonmagnetic former. An emf of 0.25V is induced in coil 1 when the flux linking with it changes at the rate of 10−3wb/sec. A current of 2A in coil 2 causes flux of 10−4wb to link coil 1. What is the mutual inductance between the coils. [5+6+5]

3. (a) Show that in a series R-L-C circuit, the resonant frequency is the geometric mean of half power frequencies.

(b) The voltage applied to a circuit and the current drawn are V= (200 – j100)V and I= (60 + j40) A respectively. Determine the circuit parameters and power dissipated.

(c) Derive the expression for i(t) when the switch S is suddenly Closed at t=0 in the circuit shown in Figure 3c. Sketch the variation of i(t) with Respect to time. [6+6+4]

Figure 3c

4. (a) For the circuit shown in the Figure 4a, find i1(t) and i2(t).The initial Voltage across the capacitor is 2V and the initial current through the inductor is Zero. Use the Laplace Transform method.

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Code No: R05010401 Set No. 2

Figure 4a

(b) Determine the current i(t) in a series R-L-C circuit with R=5Ω L=1/2H, C=1/4F with the Voltage applied is a ramp Voltage V(t)=10 r(t-2). Assume initially the circuit is relaxed. [10+6]

5. (a) State and explain superposition theorem?

(b) Is superposition theorem valid for power? Substantiate your answer?

(c) Determine the current in the 1Ω resistor across A, B of the network shown in Figure 5c using superposition theorem. [4+4+8]

Figure 5c

6. (a) Find the y-parameters of the network shown in Figure 6a and there by obtain z-parameters.

Figure 6a

(b) Obtain the expressions to get symmetry and reciprocity of a given network in terms of g-parameters. [12+4]

7. (a) Draw the circuit of asymmetrical T-attenuator. Write the design equation for the circuit resistances in terms of

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Code No: R05010401 Set No. 2

i. the image resistances and

ii. the image transfer constant θ.

(b) Design an asymmetrical T-attenuator to produce attenuation of 20 DB and to work between source impedance of 400Ω and load impedance of 900Ω. [10+6]

8. What is constant k band pass filter? Explain the design procedure o this filter? [16]

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Code No: R05010401 Set No. 3

I B.Tech Semester Supplimentary Examinations, June 2009 NETWORK ANALYSIS

( Common to Electronics & Communication Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering, Electronics &

Telematics and Electronics & Computer Engineering) Time: 3 hours Max Marks: 80

Answer any FIVE Questions All Questions carry equal marks

⋆ ⋆ ⋆ ⋆ ⋆

1. (a) Draw the wave forms of iR ,iL and iC for the circuit shown in Figures 1a & 1a, When it is excited by a Voltage source having a wave form shown below.

Figure 1a

Figure 1a

(b) What is an incidence matrix? What are cutset and Tieset matrix? Illustrate with a suitable example.

(c) Draw the dual of the Network shown in Figure 1c.

Figure 1c

2. (a) Explain the dot convention for magnetically coupled coils and mark the dotted ends for the coils shown on the magnetic core (Figure 2a). Using different symbols.

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Code No: R05010401 Set No. 3

Figure 2a

(b) The numbers of turns in two coupled coils are 600 and 1700 turns respectively. When a current of 6A flow in coil 2 the total flux in the coil is 0.8mwb and the flux linking with the first coil is 0.5mwb.Calculate L1, L2,M and coefficient of coupling.

(c) A1500 turns coil surrounds a magnetic circuit which has a reluctance of 6*106

AT/wb. Calculate the inductance of the coil. [5+7+4]

3. (a) Define Q-factor. Derive an equation showing the relation between Q-factor and bandwidth. What is selectivity? How it is related to Q-factor.

(b) In the circuit (Figure 3b) shown, the switch is closed on the position 1 at t=0 there by applied a D.C voltage of 100V to series R-L circuit. At t=500µsec, the switch is moved to position 2 obtain the expression for current i(t) in the both intervals sketch i(t).

Figure 3b

(c) Obtain the branch currents and total current in the circuit (Figure 3) shown if applied voltage is 150⊥450V and draw the phasor diagram. [5+7+4]

Figure 3

4. (a) The switch in the circuit (Figure 4a) shown is closed at t=0.The excitation V(t)=0.1 e−3tu(t). Assuming relaxed conditions, for the circuit, determine i(t) for t >0 Use LaplaceTransform method.

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Code No: R05010401 Set No. 3

Figure 4a

(b) Find the RMS and Average values of the wave form it Vm =100Volts.(Figure 4) [8+8]

Figure 4

5. (a) How do you say duality exists between Thevenins theorem and Norton’s the- orem?

(b) Determine the current through 2.5Ω resistor using Thevenin’s theorem in the network shown in Figure 5b.

Figure 5b

(c) For the above circuit shown in Figure, Draw the Nortons equivalent circuit across x and y terminals. [4+8+4]

6. (a) Obtain the expressions of ABCD parameters in terms of z parameters.

(b) Determine the ABCD parameters of given network as shown in Figure 6. [6+10]

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Code No: R05010401 Set No. 3

Figure 6

7. (a) Draw the circuit of symmetrical Π-attenuator. Derive the design equations giving the series and shunt arm resistors in terms of

i. the characteristic impedance R0.

ii. the current ratio N.

(b) If the ratio of R1 and R2 of a symmetrical T-network is 1/4. Find the ratio of the input current to the output current. Also, calculate the attenuation in dB. [10+6]

8. Draw the circuit diagram of a Band pass filter? Explain the design procedure of the above filter in detail? [16]

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Code No: R05010401 Set No. 4

I B.Tech Semester Supplimentary Examinations, June 2009 NETWORK ANALYSIS

Telematics and Electronics & Computer Engineering) Time: 3 hours Max Marks: 80

Answer any FIVE Questions All Questions carry equal marks

⋆ ⋆ ⋆ ⋆ ⋆

1. (a) Distinguish between

i. Active and Passive elements

ii. Independent and dependent sources

(b) Find I1 ,I2 and V in the network shown in Figure 1b. Using nodal analysis.

Figure 1b

(c) Obtain the basic cutset matrix for the network graph shown in Figure 1 and hence write down the network equations,Take 1,2,3 as Tree branches. [4+8+4]

Figure 1

2. (a) Explain the Dot Convention for mutually coupled coils.

(b) Derive the Expression for coefficient coupling between pair of magnetically coupled coils.

(c) Write the Loop Equations for the Coupled circuit shown in Figure 2.[3+5+8]

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Code No: R05010401 Set No. 4

Figure 2

3. (a) A series R-L-C circuit has a resistance of 8Ω and resonates at 250Hz. Band- width of the circuit is 50Hz. Determine the values of L and C in the circuit.

(b) A sinusoidal voltage 25sin 10t is applied at Time t=0 to a series R-L circuit having R=5Ω and L=1H Find i(t) and sketch it .Assume Zero current through the inductor before applying the voltage. [6+10]

4. (a) The switch in the circuit (Figure 4a) shown is closed at t=0.The excitation V(t)=0.1 e−3tu(t). Assuming relaxed conditions, for the circuit, determine i(t) for t >0 Use LaplaceTransform method.

Figure 4a

(b) Find the RMS and Average values of the wave form it Vm =100Volts.(Figure 4) [8+8]

Figure 4

5. (a) State and explain Milliman’s theorem?

(b) Obtain VAB by Milliman’s theorem and verify your result by Thevenin’s the- orem. Refer Figure 5. [6+10]

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Code No: R05010401 Set No. 4

Figure 5

6. (a) Find the y-parameters of the network shown in Figure 6a and there by obtain z-parameters.

Figure 6a

(b) Obtain the expressions to get symmetry and reciprocity of a given network in terms of g-parameters. [12+4]

7. (a) For a standard T section, show that Zo(T ) is given by

√

z1z2

(

1 + z1 4z2

)

(b) For a T-network, the total series inductance in 40 mH and the total shunt capacitance is 0.2 µF. Calculate

i. cut off frequency

ii. the image impedance

iii. Attenuation constant and phase constant at 3500 Hz and 4500 Hz. [6+10]

8. What is high pass filter? In what respects it is different from a low pass filter? Derive the equation to find the inductances and capacitances of a constant k high pass filter? [16]

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