MTT15

MTT15
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3.
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4.
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5.
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6.
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8.
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10.
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P.T.O
2
Useful constants
Electron mass (m0)
: 9.10 × 10-31 kg
Electron charge (q)
: 1.60 × 10-19 C
Planck’s constant (h)
: 6.62 × 10-34 m2kg/s
Boltzmann constant (kB)
: 1.38 × 10-23 J/K
Permittivity of free space ( ) : 8.85 × 10-12 
Permeability of free space ( ) : 4π × 10-7 H/m
3
F/m
4
001.
The solution of the differential equation given below with initial conditions
y( 0 )  4 and y (0)  5 is
d 2 y dy

 2y  0
dx 2 dx
x
A. y  (3  )e 2 x
2
2x
e
B. y 
2
C. y  3e 2 x
x
2 x
D. y  e  3e
002.
If A=
, then A-1 = ?
A.
B.
C.
D.
003.
(1+i)6 = ?
A. -4i
B. 16
C. 4i
D. - 8i
004.
(logx xy) (logxy xy) = ?
A. 1
B. x
C. y
D. xy
5
005.
The trigonometric Fourier series of an even function does not have the
A.
B.
C.
D.
006.
dc term
sine terms
cosine terms
odd harmonic term
The Fourier transform of
, where
is unit step function is
A.
B.
C.
D.
007.
From a group of 10 persons consisting of 5 lawyers, 3 doctors and 2 engineers, four
persons are selected at random. The probability that the selection contains at least one of
each category is
A.
B.
C.
D.
008.
The Laplace transform of the function
A.
B.
C.
D.
6
is
009.
Determinant of
A.
B.
is
0
1
C.
D.
010.
The eigenvalues of the matrix
A.
B.
C.
D.
011.
are
0, 1, 1
0, ±
0, 1, 2
0, ±
The series
(for : -1< x < 1)
coresponds to the the expansion of
A.
B.
C.
D.
012.
Which of the following function represents the graph shown in figure?
2
A. y   x  1
B. y  
y
1
x
x
x
C. y  e  1
D. y  e
013.
x
implies that
A.
B.
C.
D.
all the three vectors are parallel
all the three vectors are mutually perpendicular
all the vectors lie in a same plane
two of the three vector are perpendicular
7
014.
The average of the function
in the interval
is
A.
B.
C.
D. 0
015.
Divergence of the function, V  xy  i   2 yz  j   3 zx  k at the point  1,1, 2  is
A.
B.
C.
D.
016.
The maximum value of f ( x)  x 3  9 x 2  24 x  5 in the interval [1,6] is
A.
B.
C.
D.
017.
46
25
41
21
The values of a, b, c such that A 
irrotational, are, respectively
A.
B.
C.
D.
018.
1
2
3
-1
3x  4 y  az  i   cx  5 y  2z  j   x  by  7z  k is
-4, 2, 1
2, 1, -4
-1, 2, -4
1, 2, -4
Which one of the following matrices is Hermitian?
0 i
A. 

 i 0 
0 i 
B. 

 i 0
 i 0
C. 

0 i 
i 0 
D. 

 0 i 
8
019.
The Fourier transform of
is
8
16   2
8
B.
16   2
4
C.
16   2
4
D.
16   2
A.
020.
Find
=
A.
B.
C.
D.
021.
If the Newton Raphson Method is used to find the positive solution of the equation
f(x)  x  2 sin x , the iteration equation is
2(sin x n  x n cos x n )
1  2 cos x n
2 x  2 sin x n  x n cos x n )
B. x n 1  n
1  2 cos x n
2(sin x n  x n cos x n )
C. x n 1 
1  2 cos x n
2(sin x n  x n cos x n )
D. x n 1  x n 
1  2 cos x n
A. x n 1 
022.
In C language, what is the output of the following code ?
main()
{
int i=-3,j=2,k=0,m;
m=++i&&++j||++k;
printf("\n%d%d%d%d",i,j,k,m);
}
A. -3 3 1 1
B. -2 3 1 1
C. -2 3 0 1
D. -2 3 0 0
9
023.
In C language, what is the output of the following code, assume location of integer ‘i’ is
1002?
main()
{
int i=3;
int *j;
j=&i;
printf("\n%u%u%u",j,*j,*(&i));
}
A. 1002 3 3
B. 1004 3 1002
C. 1004 1002 3
D. 3 3 3
024.
In C language, what is the output of the following code?
int main()
{
int i=3, *j, k;
j = &i;
printf("%d\n", i**j*i+*j);
return 0;
}
A. 27
B. 9
C. 30
D. 3
025.
In C language, the statement used to send back any value to the calling function is
A.
B.
C.
D.
026.
The process of repeating a group of statement in an algorithm is known as
A.
B.
C.
D.
027.
return
continue
break
exit
sequence
flow
selection
iteration
Simplify the Boolean Expression F = C (B +C) (A+B+C)
A.
B.
C.
D.
A
B
C
1+AB
10
028.
The loop in which the statements within the loop are executed at least once is called
A.
B.
C.
D.
029.
The control automatically passes to the first statement after the loop in
A.
B.
C.
D.
030.
then the statement
assigns a value 5 to p
assigns a value 7 to p
gives an error message
assigns a value 8 to p
Keywords can be used as variable names
Variable names can contain a digit
Variable names do not contain a blank space
Capital letters can be used in variable names
A typical modern computer uses
A.
B.
C.
D.
034.
and
Which of the following is FALSE in C?
A.
B.
C.
D.
033.
unary operator
relational operator
comparison operator
ternary operator
In C language, if
A.
B.
C.
D.
032.
break statement
continue statement
switch statement
if statement
‘C’ allows a three-way transfer of control with the help of
A.
B.
C.
D.
031.
while
do-while
for
if
magnetic tape for primary memory
more than 10, 000 vaccum tubes
magnetic cores for secondary storage
LSI chips
Which of the following memories has shortest access time?
A.
B.
C.
D.
Magnetic Bubble Memory
Magnetic Core Memory
Cache Memory
RAM
11
035.
Which of the following statements should be used to obtain a remainder after dividing
3.14 by 2.1 in C language?
A.
B.
C.
D.
036.
How would you round off a value from 1.66 to 2.0 in C language?
A.
B.
C.
D.
037.
roundoff(1.66)
roundup(1.66)
floor(1.66)
ceil(1.66)
A computer program that converts entire program into machine language is called
A.
B.
C.
D.
038.
rem = fmod(3.14, 2.1);
rem = 3.14 % 2.1;
rem = modf(3.14, 2.1);
Remainder cannot be obtain in floating point division.
Interpreter
Simulator
Compiler
Commander
The ALU of a computer responds to the commands coming from
A.
B.
C.
D.
039.
A bulb rated at 60W, 120V is used for 30 minutes. The charge associated with this
operation is
A.
B.
C.
D.
040.
Control section
Primary memory
External memory
Cache memory
3600 C
7200 C
60 C
900 C
The current wave shape shown in figure (a) is applied to a circuit element. The voltage
across the element is shown in figure (b). The element is
V
i
0
4S
0
t
Figure (a)
4S
t
Figure (b)
12
A.
B.
C.
D.
041.
In a purely capacitive circuit, the phase relationship between current and voltage is
A.
B.
C.
D.
042.
Z11 = Z22
AD-BC = -1
BC-AD = -1
h12 = h21
A series LCR circuit has a resonance frequency of 1 kHz and a quality factor of
Q = 100. If each of R, L and C is doubled from its original value, the new Q of the
circuit is
A.
B.
C.
D.
045.
source impedance, Zs
real part of Zs
imaginary part of Zs
complex conjugate of Zs
A two-port network is reciprocal for which of the following condition
A.
B.
C.
D.
044.
voltage leads the current by 90.
current leads the voltage by 180.
current leads the voltage by 90.
voltage leads the current by 180.
If an impedance ZL is connected across a voltage source V with source impedance Zs,
then for maximum power transfer, the load impedance must be equal to
A.
B.
C.
D.
043.
an inductor
a resistor
a capacitor
a semiconductor
25
100
200
50
An circuit consists of a resistance, R=20 k, inductance L=250 mH in series with a
40 mV battery and switch. If the switch is closed at t  0 , the current in the circuit varies
with time as
A.
B.
C.
D.
13
046.
If the Laplace transform of the voltage across a capacitor of value 0.5 F is
The value of the current through the capacitor at t= 0+ is
A. 0 A
B. 2 A
C.
A
D. 1 A
047.
A ramp voltage, V(t) = 100t volts is applied to an RC differentiating circuit with
R = 5 kΩ and C = 4µF. The maximum output voltage is
A.
B.
C.
D.
048.
Two port networks are connected in cascade. The combination is to be represented as a
single two-port network, by multiplying the individual
A.
B.
C.
D.
049.
ABCD parameter
Z- parameter matrices
h- parameter matrices
Y- parameter matrices
The average power delivered to an impedance (4-3j)Ω by a current 5cos(100πt +100) A
is
A.
B.
C.
D.
050.
0.2 V
10 V
2V
50 V
44.2 W
62.5 W
50 W
125 W
The transfer function
of the circuit given below in Laplace domain is
A.
B.
14
C.
D.
051.
The poles of the impedance Z(s) for the network shown below will be real and
coincident if
A.
B.
C.
D.
052.
The current
in the network given below is,
A.
B.
C.
D.
053.
A network N is to be connected to load of 500 ohms. If the Thevenin’s equivalent
voltage and Norton’s equivalent current of N are 5Volts and 10mA respectively, the
current through the load is
A.
B.
C.
D.
054.
A voltage of
volt is applied to an inductance of
power in watts across the inductor is
A.
B.
C.
D.
15
. The instantaneous
055.
Find the transmission parameters for a two port network, if the ‘Z’ parameters are given
by
A.
B.
C.
D.
056.
A graph of an electrical network has 3 nodes and 9 branches. The number of links (l) ,
with respect to the chosen tree, would be
A.
B.
C.
D.
057.
7
6
5
8
A capacitor
is connected in parallel with a capacitor
and the
combination is connected across a time varying voltage source. At a particular time, the
current supplied by the source is 5 A. The magnitude of instantaneous currents
through the individual capacitors is
A.
B.
C.
D.
058.
Energy stored in the capacitor of
A.
B.
C.
D.
059.
shown in the circuit under dc conditions is
µ
µ
µ
If each of the resistances in the network shown below is R, what is the resistance
between terminals A and B?
A.
B.
C.
D.
2R
R/2
R/3
R
16
060.
In a series RLC circuit with
, L=1 H and
, the resonant frequency is
4
A. 2 10 Hz
4
B. 10 Hz
1
10 4 Hz
C.
D. 2
061.
The induced electric field at x = 0 in an n-type semiconductor in thermal equilibrium at
300K
due
to
linear
variation
in
donor
doped
concentration
for the range
is
A.
B.
C.
D.
062.
107 cm/s. If the length of
3 GHz
6.25 GHz
3.45 GHz
2.75 GHz
For a 0.6 µm thick n-channel GaAs MESFET, the estimated internal pinch-off voltage is
0.5 V. If the thickness of channel is increased by 20%, the internal pinch-off voltage is
A.
B.
C.
D.
065.
-6.60 × 103 V/cm
-3.32 × 103 V/cm
-1.32 × 104 V/cm
0 V/cm
In an n-channel MOSFET, the velocity of an electron is 1.57
the channel is 4 m, the maximum operating frequency is
A.
B.
C.
D.
064.
51.8 V/cm
12.8 V/cm
25.9 V/cm
0 V/cm
For a built-in potential of 0.63 V in silicon based p-n junction, the total space charge
region width is 0.95 µm. The maximum electric field present in the junction is
A.
B.
C.
D.
063.
10 4 Hz
1.0 V
0.34 V
0.72 V
0.41 V
The high input impedance of Junction Field Effect Transistor (JFET) amplifier is due to
A.
B.
C.
D.
the source and drain being far apart
its very low gate current
the pinch-off voltage
the geometry of the FET
17
066.
If the energy of an electron is greater than '
called
A.
B.
C.
D.
067.
0.51 1016 cm-3
1 1016 cm-3
1.6 1016 cm-3
0.75 1016 cm-3
The effective mass of an electron in density of states of a semiconductor
A.
B.
C.
D.
069.
-1.5 m
-0.12 m
1.1 m
2.3 m
The power in Gunn diode based oscillator is
A.
B.
C.
D.
071.
can be increased or decreased
can never be decreased
can never be increased
depends on its spin
A doped germanium crystal of length 2 cm, breadth 1 cm and width 1 cm, carries a
current of 1 mA along its length parallel to +x axis. A magnetic field of 0.5 T is applied
along +z axis and the Hall voltage of 6 mV is measured with negative polarity at y = 0
plane. The Hall resistance is
A.
B.
C.
D.
070.
cold electron
hot electron
reduced mass electron
None of the above
If the mobility of electrons in an n- type semiconductor is 3125 cm2V-1sec-1, the required
density of donor atoms to make an intrinsic germanium specimen to a n-type
semiconductor of conductivity 5 mho/cm is
A.
B.
C.
D.
068.
' above the Fermi energy, the electron is
inversely proportional to f2
directly proportional to f2
inversely proportional to f
directly proportional to f
The mobility of charge carriers in a semiconductor due to ionized impurities is
A.
B.
C.
D.
directly proportional to T 3/2
inversely proportional to T 3/2
directly proportional to T 1/2
directly proportional to T 5/2
18
072.
The intrinsic carrier concentration of germanium at room temperature is 2.5 1019 m-3.
It is doped with phosphorus at a rate of 1 phosphorus atom per million atoms of
germanium. If the concentration of germanium atoms is 5
1028 m-3 for complete
ionization of phosphorus atoms, the hole concentration is
A.
B.
C.
D.
073.
6.093 ps
0.885 ps
0.596 ps
22.264 ps
A system has a receiver noise of 50 . It is connected to an antenna with an input
resistance of 50 . The noise figure of the system is
A.
B.
C.
D.
077.
drift current
diffusion current
recombination current
induced current
What is the dielectric relaxation time constant for carrier in n-type doped Si with
conductivity of 1.17 / Ω-cm? (Assume permittivity of Si is 11.7)
A.
B.
C.
D.
076.
0.48 A/cm2
1080 A/ cm2
108 A/cm2
48 A/cm2
Under low level injection assumption, the injected minority carrier current for an
extrinsic semiconductor is essentially the
A.
B.
C.
D.
075.
1016 m-3
1016 m-3
1016 m-3
1016 m-3
In an n type GaAs at T = 300 K, the electron concentration varies linearly from 1 1018
to 7
1017 cm3 over a distance of 0.10 cm. If the electron diffusion coefficient
Dn = 225 cm2/s, the diffusion current density is
A.
B.
C.
D.
074.
7.25
8.65
4.05
1.25
1
50
2
101
The carrier signal c(t) and the message signal m(t) are used to generate an AM signal.
The modulation index of the generated AM signal is 0.5. The quantity
is
A.
B.
C.
D.
1/4
1/6
1/2
1/8
19
078.
The power transmitted in lower side band of an AM signal with total power content as
1000 W and the percentage modulation being 100 % is:
A.
B.
C.
D.
079.
An RF amplifier with a gain of 20 dB and a noise factor of 2.5 is operating over a
bandwidth of 30 MHz at 27 oC. The noise power at the output of this amplifier is
A.
B.
C.
D.
080.
24 kHz
30 kHz
12 kHz
18 kHz
In a PCM system, 24 telephone channels, each limited to band 3.4 kHz are time
multiplexed for 128 quantization levels and 8 kHz sampling frequency. The bandwidth
in this PCM system is nearly
A.
B.
C.
D.
083.
9 µV
7 µV
10 µV
15 µV
Nyquist bandwidth in case of a PCM sampling at 8000 sample/s and using 6-bits/word
for transmission is
A.
B.
C.
D.
082.
33.57 pW
28.96 pW
31.05 pW
40.34 pW
An amplifier operating over the frequency range from 7 to 14 MHz has a 700  input
resistance at the ambient temperature 27 oC. The rms noise voltage at the input to this
amplifier is
A.
B.
C.
D.
081.
250 W
166.6 W
333 W
500 W
1.5 MHz
1.0 MHz
2.5 MHz
3.1 MHz
For a QPSK signal, the baud rate for a bit rate of 800 bps is
A. 100
B. 450
400
C.
D. 200
20
084.
A communication channel has a bandwidth of 100 MHz. The channel is extremely noisy
such that the signal power is very much below the noise power. The capacity of this
channel is
A.
B.
C.
D.
085.
Johnson noise voltage is 0.25 µV for a receiver operating in a bandwidth of 3 kHz at
27 C temperature. In bandwidth of 48 kHz, the same receiver has a Johnson noise
voltage of
A.
B.
C.
D.
086.
087.
2.25 µV
0.25 µV
1 µV
0.5 µV
A phase modulation transmitter is operating with a carrier of frequency 100 MHz and
carrier voltage of 8 V. The modulating signal has amplitude of 2 V and a frequency of 6
kHz resulting in a deviation of 60 kHz. The phase modulated voltage equation is
A.
π
B.
π
C.
π
D.
π
π
π
π
π
A BPSK modulator is operating with a carrier frequency of 70 MHz and an input bit rate
of 10 Mbps. The maximum upper side and minimum lower side frequencies are
A.
B.
C.
D.
088.
50 Mbps
nearly 0 bps
100 Mbps
2400 bps
75 MHz, 65 MHz
70 MHz, 65 MHz
75 MHz, 60 MHz
70 MHz, 60 MHz
In a 16-bit QAM modulator, an input data rate fb is equal to 10 Mbps and a carrier
frequency of 70 MHz. The minimum Nyquist bandwidth is
A.
B.
C.
D.
1.25 MHz
5 MHz
2.5 MHz
7.5 MHz
21
089.
A 8-bit PSK system is operating with an information bit rate of 24 kbps. The bandwidth
efficiency of this system is
A.
B.
C.
D.
090.
For a system having 1 Hz bandwidth, the noise power at room temperature (T = 27 C)
is -174 dBm . If the band width of this system increases to 10 MHz, the noise power is
A.
B.
C.
D.
091.
44 dBW
64 dBW
57 dBW
74 dBW
For a binary FSK signal with a mark frequency of 49 kHz, a space frequency of 51 kHz,
and an input bit rate of 2 kbps, the minimum bandwidth of the signal will be
A.
B.
C.
D.
093.
-104 dBm
-70 dBm
-174 dBm
0 dBm
An earth station transmitter is transmitting an output power of 40 dBW with the help of
antenna of 40 dB gain. The backoff loss and the total branching and feeder losses are 3
dB each. The effective isotropic radiated power of transmitter is
A.
B.
C.
D.
092.
3 bits/s/Hz
8 bits/s/Hz
6 bits/s/Hz
4 bits/s/Hz
2 kHz
4 kHz
6 kHz
8 kHz
In amplitude modulation, the efficiency () for 50% modulation is
A.
B.
C.
D.
50 %
22.22 %
11.11 %
19.6 %
22
094.
In the circuit shown below, the input signal of first AM modulator is message signal
m(t) and input signal of second AM modulator is inverted m(t). The final output S(t) is
m(t)
m(t )
AM
modulator
S(t)
Vc cosω c t
Vc cosω c t
Inverted m(t)
AM
modulator

Oscillator
-
+
--
 - m(t)
A.
B.
C.
D.
095.
In SSB-SC technique, the modulation index is decreased from 100% to 70 %. The
percentage saving in the side band power is
A.
B.
C.
D.
096.
30 %
70 %
68 %
51 %
A Doppler radar operating at 12 GHz is intended to detect target velocities ranging from
1 to 20 m/s. The required passband of the Doppler filter is
A.
B.
C.
D.
097.
Two amplifiers each with 40 dB gain are connected in cascade. The noise figure of first
amplifier is 10 dB and second amplifier is 20 dB. The overall noise figure of the
cascaded system is
A.
B.
C.
D.
23
098.
A
FM
wave
is
wave is
represented
by
the
voltage
equation
The maximum frequency deviation of this FM
A.
B.
C.
D.
099.
The antenna current of an AM transmitter is 8 A when only the carrier is sent, but it
increases to 24 A when the carrier is modulated by a single sine wave. The modulation
index of AM wave is
A.
B.
C.
D.
100.
Twenty four voice signals are sampled uniformly and then time division multiplexed.
The highest frequency component for each voice signal is 3.4 kHz. The bit rate of the
system is 1.5 Mbps. If the signals are pulse code modulated with an 8 bit encoder, the
sampling rate is
A.
B.
C.
D.
101.
Which type of error detection technique uses binary division?
A.
B.
C.
D.
102.
The sequence of the binary digits representing the outcomes of parity checks in
Hamming codes is known as
A.
B.
C.
D.
103.
Check sum checking
Parity check
Longitudinal redundancy checking
Cyclic redundancy checking
look up entry
syndrome
hamming distance
radix
Rather than sending the absolute value of each sample, it is possible to achieve a smaller
transmission bit rate by sending the difference between consecutive samples. This is
known as
A.
B.
C.
D.
delta sigma modulation
delta modulation
adaptive delta modulation
pulse code modulation
24
104.
On which of the following parameter/s does the effective propagation of a signal
through wireless medium depend?
A.
B.
C.
D.
105.
In the circuit shown below, the npn transistor Q has a very high value of  . The
required value of R2 in k to produce Ic=1 mA is
A.
B.
C.
D.
106.
Medium through which the signal propagates
Antenna size only
Signal wavelength only
Relative size of antenna and signal wavelength
30
10
20
40
A coaxial cable is made of two brass conductors. The spacing between the conductors is
filled with Teflon (  r  2.1, tan   0 ). Which of the following circuits can represent the
lumped element model of a small length  z of the cable?
A.
B.
C.
D.
25
107.
Which of the following represents the electric field lines of the TE02 mode of the
rectangular waveguide shown in the figure?
A.
B.
C.
108.
Consider a 3 m long air filled lossless transmission line with characteristic impedance of
50 . If it is terminated by a short circuit and is excited with the frequency of 37.5 MHz,
the input impedance Z i is
A.
B.
C.
D.
109.
D.
capacitive
open
short
inductive
A plane wave propagating in air with
V/m is incident on a perfectly

conducting slab positioned at x  0 . The E of the reflected wave is given by
A.
B.
C.
D.
110.
A 25 dBm power in Watts is equal to
A.
B.
C.
D.
111.
V/m
V/m
V/m
V/m
0.96 W
0.316 W
0.4 W
0.16 W
If  is the amplitude attenuation coefficient in nepers/m of a propagating
electromagnetic wave, the attenuation in dB/m is
A. 0.434 
B. 4.343 
C.

0.8686
D. 8.686 
26
112.
For a lossy distortionless transmission line, the attenuation coefficient  is given by
A.  LC
B. RG
R
G
G
R
C.
D.
113.
A pure resistance RL when connected at the load end of a 100 ohm transmission line
produces a VSWR of 2. The value of RL in ohms can be
A.
B.
C.
D.
114.
If the impedance of a series resonant circuit is inductive at f = 1000 Hz, it will be
capacitive at some frequency f, where
A.
B.
C.
D.
115.
4
10
1
20
The modes of a rectangular waveguide are denoted by TEmn or TMmn where m and n
define the number of half cycles along the larger and smaller dimensions respectively.
Which of the following statements is TRUE?
A.
B.
C.
D.
117.
f > (1000- f0) Hz
f = 1000 +f0 Hz, where f0 is the resonance frequency
f < (1000- f0) Hz
f = f0 Hz, where f0 is the resonance frequency
A parallel RLC resonant circuit has R = 4 , L = 4 H and C = 0.25 F. The value of Q of
the circuit is
A.
B.
C.
D.
116.
only 50
only 200
400 or 200
50 or 200
The TE10 mode does not exist
The TM10 and TE10 modes both exist and have the same cut-off frequency
The TM10 and TM01 modes both exist and have the same cut-off frequency
The TM10 mode does not exist
The input impedance of a short circuited transmission line of length λ/8 having
Z0 = 50 Ω is
A.
B.
C.
D.
j 50 2 Ω
j 400 Ω
j50 Ω
j 50 2 Ω
27
118.
A transmission line has a characteristic impedance of 50 Ω and a resistance of 0.1Ω/m.
If the line is distortionless, the attenuation constant (in Np/m) is
A.
B.
C.
D.
119.
A lossless transmission line is terminated in a load which reflects a part of the incident
power. The measured VSWR is 2. The percentage of the power that is reflected back is
A.
B.
C.
D.
120.
0.002
500
5
0.014
11.11
33.33
0.11
57.73
The capacitance per unit length and the characteristic impedance of a lossless
transmission line are C and Z0 respectively. The phase velocity of travelling wave on the
transmission line is
A. Z o C
C
B.
Zo
1
C.
Z oC
Z
D. o
C
121.
The input impedance of a lossless transmission line is 100 Ω when terminated in a short
circuit and 64 Ω when terminated in an open circuit. The characteristic impedance of
the line is
A.
B.
C.
D.
122.
164 Ω
36 Ω
64 Ω
80 Ω
A sinusoidal electric field intensity of amplitude 250 V/m with frequency 1 GHz exists
in a lossy dielectric medium of effective conductivity 1.39 × 10-4 S/m. The power
dissipated per unit volume is
A.
B.
C.
D.
8.68 W/m3
1.62 W/m3
4.34 W/m3
3.86 W/m3
28
123.
If the electrostatic potential at a point
is given by
3
electrostatic energy density at that point (in J/m ) is
volt, the
A.
B.
C.
D.
124.
The minimum frequency of an electromagnetic wave, which can propagate along a
hollow, metallic waveguide whose cross-section is a square of side W (c is the velocity
of light) is
A.
B.
C.
D.
125.
The time average Poynting vector is related to the amplitude of the electric field by the
following relation
A.
S  c 0 E 0
B.
c
S   0 E02
2
S   0 E 02
C.
D.
126.
π
c
S   0 E0
2
A quarter wave transformer designed using a dielectric (r = 9) filled coaxial line is
required to transform load impedance ZL= 120  to input impedance Zin= 50  at 2
GHz. The length of this transformer is
A.
B.
C.
D.
4.16 mm
112.5 mm
12.5 mm
50 mm
29
127.
Frequency tuning in a reflex klystron is obtained by varying
A.
B.
C.
D.
128.
A parabolic antenna is operating at 5 GHz and has a half power point beamwidth of 10.
The antenna power gain as a ratio is
A.
B.
C.
D.
129.
7.5
15
12.5
20
471.25 
301.6 
62.50 
40 
A lossless transmission line with characteristic impedance 100  is excited by a signal
of voltage 100 V at 1.2 MHz. If the line is terminated by ZL(= Z0 ) at a distance 1 km,
the voltage in volts at the midpoint of the line is
A. 10 e

j4

j8
B. 20 e
C. 5e

j4
D. 100 e
132.
6 cm and is operating at
An air-filled rectangular waveguide has cross-section dimensions of width a = 25 mm
and height b = 11 mm. The characteristic impedance of the dominant mode at 10 GHz
is
A.
B.
C.
D.
131.
490
294
160
320
A pyramidal horn antenna has aperture dimensions of 12
5 GHz. The beamwidth of this antenna is
A.
B.
C.
D.
130.
positive voltage applied to the anode
negative voltage applied to the cathode
RF signal applied to RF output electrode
negative voltage applied to the repeller

j8
An air-filled rectangular waveguide section of length 1.5 cm is used as a quarter wave
transformer at operating frequency of 10 GHz. The broad dimension of a waveguide in
its dominant mode is
A.
B.
C.
D.
2.28 cm
1.50 cm
1.73 cm
3.07 cm
30
133.
A lossless 50  coaxial air line is terminated with a short load. The successive first two
voltage minimas are at 1.25 cm and 7.25 cm from the load end. The frequency of
operation is
A.
B.
C.
D.
134.
In a microwave mixer, the incoming RF signal and a local oscillator signals are fed to
A.
B.
C.
D.
135.
3.0 GHz
1.5 GHz
2.5 GHz
3.5 GHz
E-arm and H-arm, respectively
E-arm and one-collinear arm, respectively
H-arm and one-collinear arm, respectively
Both collinear arm.
Two coaxial cables are filled with different dielectric constants εr1 and εr2 respectively.
The ratio of the wavelengths in the two cables (λ1/ λ2) is
A.
 r1  r 2
B.  r1  r 2
C.
 r 2  r1
D.  r 2  r1
136.
In an impedance Smith chart, a clockwise movement along a constant resistance circle
gives rise to
A.
B.
C.
D.
137.
If the electric field intensity associated with a uniform plane electromagnetic wave
travelling
in
a
perfect
dielectric
medium
is
given
by
V/m, the velocity of the travelling waves is
A.
B.
C.
D.
138.
decrease in the value of reactance
no change in the reactance value
increase in the value of reactance
no change in the impedance value
3 108 m/sec
6.2 108 m/sec
2 107 m/sec
2 108 m/sec
A rectangular metal wave guide filled with a dielectric material of relative permittivity
εr = 4 has the inside dimensions 3.0 cm
1.2 cm. The cut-off frequency for the
dominant mode is
A.
B.
C.
D.
5.0 GHz
10.0 GHz
2.5 GHz
12.5 GHz
31
139.
In the case of reflection and refraction of light at the dielectric interface
A.
B.
C.
D.
140.
tangential components of D and B are continuous
tangential components of D and normal component of B are continuous
normal components of D and B are continuous
normal components of D and tangential component of B are continuous
An electromagnetic wave is propagating in free space in the z direction. If the electric
field is given by
where
, the magnetic field is
A.
B.
C.
D.
141.
142.
A parallel plate capacitor with plate area 5 cm2 and plate separation 3 mm has a voltage
of 50sin103t applied to its plates. If ε = 2εo, the displacement current is
A. 210 cos 103t nA
B. 150 sin 103t nA
C. 120 cos 103t nA
D. 147 cos 103t nA
In a non magnetic medium
for which E 4sin  2 x107t  0.8x  k V/m, the value of εr is
A.
B.
C.
D.
143.
A 250 MHz, 40 V peak signal is incident on a 72  transmission line. The phase
velocity of the signal in this transmission line is 0.8c, where c is speed of light. The
wavelength of the signal on line is
A.
B.
C.
D.
144.
14.5
42.5
11.5
22.5
1.2 m
0.24 m
1.5 m
0.96 m
A quarter wave transformer is used for the purpose of matching a 100  load to a
transmission line having L = 1.35 H/m and C = 60 pF/m. The characteristic impedance
of matching transformer is
A.
B.
C.
D.
377 
100 
150 
122. 47 
32
145.
A radar pulse sent to a target returns after 20 s. The distance of the target from the
radar is
A.
B.
C.
D.
146.
The propagation coefficient for a transmission line is (0.0005 + j π/10) m-1. The
attenuation in nepers for a 50 m line is
A.
B.
C.
D.
147.
377 
120 
0
72 
-25 dBm
-10 dBm
-35 dBm
0 dBm
A transmission line is connected to a load of reflection coefficient 0.2. If the measured
voltage across the load is 30V, the incident voltage is
A.
B.
C.
D.
150.
V/m is propagating in a medium with
An optical fibre cable with 0.25 dB/km loss is connected to 0.1 mW light source. The
optical power at 100 km from the source is
A.
B.
C.
D.
149.
0.0005 Np
0.217 Np
25 Np
0.025 Np
A plane wave with
r = 1. The wave impedance of the medium is
A.
B.
C.
D.
148.
3 km
2.4 km
10.8 km
1.5 km
150 V
15 V
100 V
25 V
Radiation resistance of a dipole antenna
A.
B.
C.
D.
80 
12 
5.5 
7.9 
33
long is
SPACE FOR ROUGH WORK
34
SPACE FOR ROUGH WORK
35
SPACE FOR ROUGH WORK
36