1.
The reduced incidence matrix of an oriented graph is given as
0 1 0 0
0 0
0 0 0 1

Draw the graph.
How many trees are possible for this graph?
Write the tie-set matrix.

Determine the overall impulse response, of the system shown in Fig. below. Given that

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where delta(n) and denote, respectively, the unit
step signals

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Derive an expression for Maxwell's equation in integral form from Ampere's law.
Two ideal and identical junction diodes are connected as shown in Fig. If the current through the reverse-biased diode is Io and is constant, explain the circuit operation when both the diodes are connected in forward-biased condition. Assume VT =25 mv, Vr=0·7 V and n=1 for the diodes.

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Two impedances Z1 5ohms and Z2 -jXc)ohms are connected in parallel and this combination is connected in series with Z3 (6·25 j1· 25)ohms.
Determine the value of capacitance of Xc to achieve resonance if the supply is 100 50 Hz.

2.
For the circuit shown in Fig. find the value of if the power dissipation in the load resistance RL is 36 watts:



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Consider a continuous-time LTI system for which the input and output are related by the following differential equation

d2y(t)/dt2

Determine the impulse response, of the system for the following cases by plotting pole-zero pattern
The system is causal.
The system is stable.
The system is neither stable nor causal.

For the circuit shown in Fig. calculate the resistance Ro seen by the output terminals. Ignore the effect of R1 and R2. Assume beta 99 and hie 1 kilo ohm Comment on the value of Ro of the circuit

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3.
Obtain the dotted equivalent circuit for the coupled circuit shown in Fig. and hence find the voltage across the capacitor


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A transmission line has the following parameters
ZL =(200-j200)ohms, Zo =200ohms
Determine the voltage standing wave ratio and reflection coefficient of the line.

Write the significance of Smith chart.
Find the length of x of the 100 Q transmission line which converts a load impedance ZL (100 +j100)ohms to a pure resistance. Also find the value of the resistance Rx. Assume VSWR 2·6.

For the circuit shown in Fig. get the expression for Also sketch the output waveform. Assume that the op-amp is ideal. R
omega(w) 1/Sqrt(LC) and Vi 10sinwt


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4.
Determine the causal signal, having its z-transform
1 z-l

Determine the propagation constant y for a material having Relative permitivity er
and sigma 0·25 if the wave frequency is 1·6 MHz.
Find the skin depth delta at a frequency of 1·6 MHz in aluminium, where
sigma 38·2 MS/m and Relative permitivity 1. Also find gaama(y) and the wave velocity u.


For the op-amp circuit shown in Fig. deduce the output voltage expression.
Calculate when R1= 1 kilo ohm R2, R3 1 kilo ohm and R4 2 Kilo ohm and Vin 1V


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If a propagating wave in free space has a potential gradient point as
E (-i-2sqrt3j+3k)e-jO·04pi(sqrt(3)x-2y-3z) V/m
then determine
the vertical direction of propagation;
the wavelength of the propagating wave;
the frequency of the propagating wave;
the phase velocity and phase velocity vector.

What are the apparent velocities and wavelengths along y and z directions?


5.
Minimize the SOP terms given for a Boolean function
f =sigma 10, 11, 12, 14, 15) Implement the minimized function using NAND gates alone.
What do you mean by V-curves of a synchronous motor? Draw them showing the leading power factor and lagging power factor regions.
The SCR shown in Fig. has a di/dt limit of 10 amp per microsec. It is to be operated from a 100 V d.c. supply with load resistance R 50 ohms.
What is the minimum value of load inductance L that will protect the SCR?
If an RsCs snubber is connected across the SCR with Rs 500 ohms, what will be the new value of load inductance L to protect the SCR against di/dt?


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(d)Compare Amplitude Modulation and Frequency Modulation

A 20 hp, 230 1150 r.p.m. d.c. shunt motor has four poles, four parallel armature paths and 882 armature conductors. The armature circuit resistance is 0·188ohms. At rated speed and rated output, the armature current is 73 A and the field current is 1·6 A. Calculate the electromagnetic torque.

6.
Identify the circuit shown in Fig. Briefly explain the same. Calculate the current i and Vo if VR=5v and 5 kilo ohms Rp

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The resistances and leakage reactances of a 10 kVA, 50 Hz, 2300/230 V distribution transformer are r1 3·96 ohms and r2 0·0396 ohms, Xl 15·8 ohms and X2 0·158 ohms
Subscript 1 refers to HV and 2 refers to LV winding The transformer delivers rated kVA at 0·8 p.f. lagging to a load on the LV side. Find the HV side voltage necessary to maintain 230 V across load terminals. Also find the percentage voltage regulation.
Explain the operations of phase-locked loop used as FM demodulator with neat sketch.

7.
What is a PLA? Realize the following functions using an appropriate PLA:
f1 =AB+CD
f2 bar B+AB bar
f3 bar D

A 200 875 r.p.m., 150 separately excited d.c. motor has an armature resistance of 0·06 ohms. The motor armature terminals are fed from a single-phase fully controlled bridge rectifier. The input a.c. supply to bridge rectifier is 240 50 Hz. Assuming continuous and ripple-free armature current,
determine the following
Firing angle of SCRs for rated torque and 750 r.p.m.
Firing angle for rated torque and -500 r.p.m.
Assume that field winding of the motor is connected to a constant d.c. voltage source.

Write a short note on white noise.
A single-phase full-bridge square-wave inverter is supplying power to a purely resistive load of 20 ohms. The d.c. source voltage is 600 V. If the inverter is to operate at 500 Hz with an r.m.s. load voltage 500 find
average power absorbed by the load;
average source current (assume no losses in switching);
average current of each switch.

8.
A 3-phase, 4-pole, 50 hp, 440 60 Hz, Y-connected induction motor has the
following parameters per phase
Xl 0·35 ohms rl =0·10 ohms,
0.40 ohms 0·12 ohms,

It is known that the stator core loss amounts to 1200 W and the rotational losses equal 950 W. Moreover, at no-load the motor draws a line current of 18 A at a power factor of 0·089 lagging. When the motor operates at a slip of find the input line current and power factor.
A class-A chopper circuit is supplied from a d.c. source voltage 100 V. The chopper supplies power to a series R-L load with R 0·5 ohms and L 1 mH. The
chopper switch is ON for 1 ms in an overall period of 3 ms. Calculate average load voltage, maximum and minimum value of load current and average load current. Assume continuous current operation of the chopper.
Explain in detail about pre-emphasis and de-emphasis in Frequency Modulation(FM).