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Code No: R5100406
I B.Tech (R05) Supplementary Examinations, June 2009 NETWORK ANALYSIS (Common to Electronics & Communication Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering and Electronics & Computer Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) Two coupled coils have self inductance L1 =50mH and L2 =200mH and coefficient of coupling of coil 2 has 1000turns and i1 =5.0 sin 400t, Calculate the voltage across coil 2 and flux φ1 produced current i1 . (b) An Iron ring has a mean diameter of 50cms and an area of C.S. of 2cm2 and is wound with an 500turns. Take the relative permeability of iron as 750. Determine i. The inductance of the coil ii. The current in the coil to establish a flux density of 1 wb/ m2 in the ring. iii. The current in the coil to establish the same flux density if an air gap 1mm is cut in the ring.
0.5. If by the coil of
[8+8]
2. (a) A series R-L-C circuit has a resistance of 8Ω and resonates at 250Hz. Bandwidth 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] 3. (a) A Voltage V Sin(wt+φ) is applied to an initially relaxed RL series circuit. Find the value of φ for which there will be no transient current in the circuit. Use Laplace Transform method. (b) Find RMS and average value of Voltage wave form shown in Figure 1. [8+8]
Figure 1: 4. (a) What is complex power? Explain in detail. (b) The current in a given circuit is I=(12-j5)A when the applied voltage is V=(160-j120)V. Determine i. the complex expression for power ii. power factor of the circuit iii. the complex expression for impedance of the circuit iv. Draw the phasor diagram. [6+10] 5. (a) What do you understand by poles and zeros of a network function? (b) Discuss the restriction on location of poles and zeros of a driving point function? (c) Plot the poles and zeros of the network function given by s(s+2) F (s) = (s+3)(s 2 +4s+5)
[5+6+5]
6. (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] 7. What is a half section? What is its main characteristic? Why it is used? Derive expression for impedances as seen from the two ports of an m-derived half section. [16] 8. What is composite filter? Draw its circuit diagram? Give a general procedure for its design? ?????
[16]
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Code No: R5100406
I B.Tech (R05) Supplementary Examinations, June 2009 NETWORK ANALYSIS (Common to Electronics & Communication Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering and Electronics & Computer Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (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] 2. (a) A coil has a resistance of 60Ω and inductance of 0.2H. What series combination RC and C connected in parallel with the coil will make the circuit resonant at all frequencies. Derive the relevant equations. (b) There are two separate coils when an voltage of 30V D.C is applied to each of the coils the currents taken are 4 and 5A When an A.C voltage of 30V is applied to each of the coils they take 1A and 2 A. If both the coils are connected in series and 100V A.C is applied across the combination, find the current and power consumed by the circuit. (c) A series R-C circuit consists of R=10Ω and C=0.1F and a D.C voltage of 20V is applied to the circuit at t=0obtain the current i(t) , VR (t) and VC (t) for t>0.Assume that the circuit is initially relaxed. [6+5+5] 3. (a) Find the Laplace Transform of single pulse shown in Figure 1.
Figure 1: (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] 4. (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] 5. (a) What do you understand by poles and zeros of a network function? (b) Discuss the restriction on location of poles and zeros of a driving point function? (c) Plot the poles and zeros of the network function given by s(s+2) F (s) = (s+3)(s 2 +4s+5) 6. (a) Define Attenuator? Explain the difference types of attenuators? (b) Design as asymmetrical L-attenuator to work with image impedances of 600Ω and 400Ω.
[5+6+5] [10+6]
7. (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] 8. (a) Explain the variation of phase shift and attenuation of constant k high pass filter. (b) Design both the T and Π sections of a high pass filter having an infinite frequency characteristics impedance of 300Ω and a cut off frequency of 2000 Hz. [8+8] ?????
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Code No: R5100406
I B.Tech (R05) Supplementary Examinations, June 2009 NETWORK ANALYSIS (Common to Electronics & Communication Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering and Electronics & Computer Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) Explain what you understand by coefficient of coupling and derive expression for it. (b) Two identical coils with L=0.02H have a coefficient of coupling of 0.8. Find mutual inductance and the two equivalent inductances with the two coils connected in series aiding and series opposing. Derive the equations employed. (c) An iron ring of 20cm diameter and 5cm2 in cross section is wound with 200 turns. The relative permeability of iron is 500. To establish a flux density of 1wb/m2, Determine the magnetizing current in the coil. [5+7+4] 2. (a) What do you understand by “Voltage Magnification” In a series resonance circuit? Derive the expression for Voltage Magnification. (b) In a two element A.C circuit the applied voltage and current taken are given as V=200sin(wt+300 ) and i=50sin(wt+600 ) find the elements of the network with their values .Also determine the active power , reactive power , apparent power taken by the circuit. (c) A series R-L circuit is excited by 100V D.C source by closing the switch at t=0 find the value of i , di/dt , d2 i/ dt2 t=0+ for R=10Ω and L=1H. The current at t=0 in the inductor was zero. [4+6+6] 3. (a) A series R-L-C circuit with R=5Ω L=0.2H, and C=1F has a Voltage source V=10 e−100t Volts applied at t=0.Find the current through the circuit using Laplace Transform method. (b) Calculate the RMS value, Average value and form factor the Voltage wave form shown in Figure 1. [8+8]
Figure 1: 4. (a) What is complex power? Explain in detail. (b) The current in a given circuit is I=(12-j5)A when the applied voltage is V=(160-j120)V. Determine i. the complex expression for power ii. power factor of the circuit iii. the complex expression for impedance of the circuit iv. Draw the phasor diagram.
[6+10]
5. (a) A typical two-port network is characterized by the equation 2V1 +4I2 =I1 and V2 +6V1 =8I2 . Determine the values of i. y11 ii. z21 and iii. h21 (b) Obtain the input and output impedances of an amplifier having h11 =2Ω; h12 =1Ω; h21 =5 and h22 =2Ω, if it is driven by a source having an internal resistance of 4Ω and is terminated through a load which draws maximum power from the amplifier. [6+10] 6. (a) Find the characteristic impedance of a symmetrical Π network. (b) A T section has a 200 ohm capacitor in each series arm and a 2000 ohm resistance in the shunt arm, find the ratio VI11 if the load resistance is i. 1000 ohm and ii. 2000 ohm. [6+10] 7. What is constant k band pass filter? Explain the design procedure o this filter? 8. What is composite filter? Draw its circuit diagram? Give a general procedure for its design? ?????
[16] [16]
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Code No: R5100406
I B.Tech (R05) Supplementary Examinations, June 2009 NETWORK ANALYSIS (Common to Electronics & Communication Engineering, Electronics & Instrumentation Engineering, Bio-Medical Engineering and Electronics & Computer Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) Explain what you understand by coefficient of coupling and derive expression for it. (b) Two identical coils with L=0.02H have a coefficient of coupling of 0.8. Find mutual inductance and the two equivalent inductances with the two coils connected in series aiding and series opposing. Derive the equations employed. (c) An iron ring of 20cm diameter and 5cm2 in cross section is wound with 200 turns. The relative permeability of iron is 500. To establish a flux density of 1wb/m2, Determine the magnetizing current in the coil. [5+7+4] 2. (a) A series R-L-C circuit has a resistance of 8Ω and resonates at 250Hz. Bandwidth 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] 3. (a) Draw the circuits of symmetrical lattice attenuator. Derive the design equations for the circuit resistances in terms of i. the characteristic impedance R0 and ii. the current ration N. (b) Design a symmetrical lattice attenuator to have attenuation of 20 DB and characteristic impedance of 500 Ω. What will be its equivalent T-structure. [10+6] 4. (a) Draw the phasor diagram for R, L, C series circuit when it is excited by sinusoidal voltage? (b) What is duality? Explain the procedure for obtaining the dual of the given planar network? (c) Draw the dual of the following network shown in Figure 1.
[6+6+4]
Figure 1: 5. (a) A typical two-port network is characterized by the equation 2V1 +4I2 =I1 and V2 +6V1 =8I2 . Determine the values of i. y11 ii. z21 and iii. h21 (b) Obtain the input and output impedances of an amplifier having h11 =2Ω; h12 =1Ω; h21 =5 and h22 =2Ω, if it is driven by a source having an internal resistance of 4Ω and is terminated through a load which draws maximum power from the amplifier. [6+10] 6. (a) Draw the circuit of symmetrical Bridged T-attenuator. Derive the design equations for the symmetrical Bridged T-attenuator. (b) Design symmetrical bridged T-attenuator with design impedance of 300Ω amd attenuation of 60dB. [10+6] 7. (a) Explain the variation of attenuation, phase shift and characteristic impedance of m derived low pass filter? (b) Design a low pass m derived T section having a cut off frequency of 2.5 KHz, a frequency of infinite attenuation 2.65 KHz and a design impedance of 600 ohm. [10+6] 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] ?????