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Q.1 – Q.5 Carry One Mark Each
Which of the following is CORRECT with respect to grammar and usage?
Mount Everest is ______
Before superlative article ‘the’ has to be used. ‘one of ’ the expression should take plural noun and so option ‘C’ and ‘D’ can’t be the answer.
The policeman asked the victim of a theft, “What did you ______?”
lose’ is verb.
Despite the new medicine’s ___________ in treating diabetes, it is not ______ widely
‘effectiveness’ is noun and ‘prescribed’ is verb. These words are apt and befitting with the word ‘medicine.’
In a huge pile of apples and oranges, both ripe and unripe mixed together, 15% are unripe fruits,
Of the unripe fruits, 45% are apples, Of the ripe ones, 66% are oranges. If the pile contains a total
of 5692000 fruits, how many of them are apples?
Michael lives 10 km way from where I live. Ahmed lives 5km away and Susan lives 7 km away from where I live. Arun is farther away than Ahmed but closer than Susan from where I live. From the information provided here, what is one possible distance (in km) at which I live from Arun’s place?
From given data, the following diagram is possible
AH = Ahmed lives; M = Michael lives
S = Susan lives; A= Arun lives
→ Arun lives farthes away than Ahmed means more than 5 km but closer than Susan means less than 7 km, from given alternatives, option ‘C’ only possible.
Q.6 – Q.10 Carry two marks each
Q.
A person moving through a tuberculosis prone zone has a 50% probability of becoming infected.
However, only 30% of infected people develop the disease. What percentage of people moving
through a tuberculosis prone zone remains infected but does not shows symptoms of disease?
In a world filled with uncertainty, he was glad to have many good friends. He had always assisted
them in times of need and was confident that they would reciprocate. However, the events of the
last week proved him wrong.
Which of the following interference(s) is/are logically valid and can be inferred from the above
passage?
(i) His friends were always asking him to help them
(ii) He felt that when in need of help, his friends would let him down.
(iii) He was sure that his friends would help him when in need.
(iv) His friends did not help him last week.
The words ‘was confident that they would reciprocate’ and ‘last week proved him wrong’ lead to statements iii and iv as logically valid inferences.
Leela is older than her cousin Pavithra, pavithra’s brother Shiva is older than Leela. When Pavithra
and shiva are visiting Leela, all three like to play chess. Pavithra wins more often than Leela does.
Which one of the following statements must be TRUE based on the above?
From given data, the following arrangement is possible
Shiva
Leela
Pavithra
Among four alternatives, option D is TRUE.
P,Q,R and S are working on a project. Q can finish the taks in 25 days, working alone for 12 hours a day. R can finish the task in 50 days, working alone for 12 hours per day. Q worked 12 hours a day but took sick leave in the beginning for two days. R worked 18 hours a day on all days. What is the ratio of work done by Q and R after 7 days from the start of the project?
Q.11 – Q.35 Carry one mark each.
Q. Let M4 = I (where I denotes the identity matrix)and M ? I, M2 ? I and M3 ? I. Then, for any
natural number k, M–1 equals:
M^{4} = I
M^{8} = M^{4} = I M^{7} = M^{1}
M^{12} = M^{8} = I M^{11} = M^{1}
M^{16} = M^{12} = I M^{15} = M^{1}
…………………..
M^{1} = M^{4K+ 3}, K is a natural number
The second moment of a Poissondistributed random variables is 2. The mean of the random variable is _____.
Given the following statements about a function f: R→R, select the right option:
P : If f(x) is continuous at x = x0, then it is also differentiable at x = x_{0}
Q : If f(x) is continuous at x = x0, then it may not be differentiable at x = x_{0}
R : If f(x) is continuous at x = x0, then it is also different at x = x_{0}
Since continuous function may not be differentiable. But differentiable function is always continuous.
Which one of the following is a property of the solutions to the Laplace equation :
Consider the plot of f(x) versus x as shown below
Suppose which one of the following is a graph of F(x)?
integration of ramp is parabolic, integration of step is ramp.
Which one of the following is an eigen function of the class of all continuoustime, linear, timeinvariant
systems (u(t) denotes the unitstep function) ?
If the input to a system is its eigen signal, the response has the same form as the eigen signal
A continuous –time function x(t) is periodic with period T. The function is sampled uniformly with
a sampling period Ts. In which one of the following cases is the sampled signal periodic ?
A discrete time signal is said to be periodic if is a rational number
Consider the sequence x[n] = a^{n} u[n] +b^{n} u[n], where u[n] denotes the untilstep sequence and 0 <
a < b <1. The region of convergence (ROC) of the ztransform of x[n] is
Consider a twoport network with the transmission matrix : If the network is
reciprocal, then
A two port network is reciprocal in transmission parameters if AD – BC = 1
i.e Determinant(T) = 1
A continuoustime sinusoid of frequency 33 Hz is multiplie with a periodic Dirac impulse train of
frequency 46 Hz. The resulting signal is passed through an ideal analog lowpass filter with a
cutoff frequency of 23Hz. The functional frequency (in Hz) of the output is _____.
f_{m} = 33Hz, f_{s} = 46Hz
The frequency in sampled signal are = 33, 13, 79, 59, 125 …… The above frequencies are passed
to a LPF of cutoff frequency 23Hz. The output frequency are = 13Hz.
A small percentage of impurity is added to intrinsic semiconductor at 300 K. Which one of the
following statements is true for the energy band diagram shown in the following figure?
Donor energy level close to conduction band.
Consider the following statements for a metal oxide semiconductor field after effect transistor
(MOSFET):
P : As channel length reduces, OFFstate current increases
Q : As channel length reduces, output resistance increases
R : As channel length reduces, threshold voltage remains constant
S: As channel reduces, ON current increases.
Which of the above statements are INCORRECT?
P: TRUE
Q: FALSE, As channel length reduces, output resistance reduces
R: FALSE: As channel length reduces, threshold voltage reduces
S: TRUE
Consider the constant current source shown in the figure below. Let ? represent the current gain of
the transistor
The load current I0 through R_{L} is
The following signal Vi of peak voltage 8V is applied to the noninverting terminal of an ideal
Opamp. The transistor has V_{BE} = 0.7 V, β = 100; V_{LED} = 1.5V, V_{CC} = 10V and –V_{CC} = – 10V.
The number of times the LED glows is –––––
V_{i }crosses 2V, 3times
Therefore the LED glows 3 times
Consider the oscillator circuit shown in the figure. The function of the network (shown in dotted
lines) consisting of the 100 k? resistor in series with the two diodes connected backtoback is to:
The circuit shown is a wein bridge oscillator. The amplitude of oscillations can be determined and stabilized by using a nonlinear control network. As the oscillations grow, the diodes start to conduct causing the effective resistance in the feedback to decrease. Equilibrium will be reached at the output amplitude that causes the loop gain to be exactly unity.
The block diagram of a frequency synthesizer consisting of Phase Locked Loop (PLL) and a
dividebyN counter (comprising /2, /4, /8, /16 outputs) is sketched below. The synthesizer is
excited with a 5 kHz signal (Input 1). The freerunning frequency of the PLL is set to 20kHz.
Assume that the commutator switch makes contacts repeatedly in the order 1234.
The corresponding frequencies synthesized are:
The output of the combinational circuit given below is
What is the voltage V_{out} in the following circuit?
Match the inferences X, Y, and Z, about a system, to the corresponding properties of the elements
of first column in Routh’s Table of the system characteristic equation.
X: The system is stable ….. P: … When all elements are positive
Y: The system is unstable … Q: … When any on element is zero
Z: The test breaks down …. R: … When there is a change in sign of coefficients
X  P, Y  R, Z Q
A closedloop control system is stable if the Nyquist plot of the corresponding openloop transfer
function
For closed loop stability Z = 0, N = P
(1, j0) should be encircled in Counter clock wise direction equaling P poles in RHP.
Consider binary data transmission at a rate of 56 kbps using baseband binary pulse amplitude
modulation (PAM) that is designed to have a raisedcosine spectrum. The transmission bandwidth
(in kHz) required for a rolloff factor of 0.25 is –––––.
A superheterodyne receiver operates in the frequency range of 58 MHz68MHz. The intermediate frequency f1F and local oscillator frequency f_{LO} are chosen such that f_{1F} f_{LO}. It is required that the image frequencies fall outside the 59 MHz – 68 MHz band. The minimum required f_{1F} (in MHz) is
f_{s} = 58 MHz– 68 MHz
When fs = 58 MHz
f_{si} = f_{s} + 21F > 68 MHz
21F > 10 MHz
1F ? 5 MHz
The amplitude of a sinusoidal carrier is modulated by a single sinusoid to obtain the amplitude
modulated signal s(t) = 5 cos 1600?t + 20 cos 1800 ?t + 5 cos 2000?t. The value of the modulation
index is –––––––.
Concentric spherical shells of radii 2m, 4m, and 8m carry uniform surface charge densities of 20
nC/m^{2}, –4 nC/m^{2} and ρs, respectively. The value of ρs (nC/m^{2}) required to ensure that the electric
flux density D = 0 at radius 10 m is –––––.
The propagation constant of a lossy transmission line is (2 +j5) m^{1} and its characteristic
impedance is (50 + j0) ? at ω = 10^{6} rad S^{1}. The values of the line constants L,C,R,G are,
respectively,
Therefore line constants L, C, R & G are respectively L = 250 μH/m, C = 0.1 μF/m, R = 100 ?/m, G = 0.04 s/m
Converting to polar coordinates, we get
A sequence x[n] is specified as
The initial conditions are x[0] = 1, x[1] = 1 and x[n] = 0 for n < 0. The value of x[12] is ––––
From the above values we can write the recursive relation as
x(n) = x(n–1) + x(n –2)
x(2) = x(1) + x(0) = 1 +1 = 2
x(3) = x(2) + x(1) = 2 +1 = 3
x(4) = x(3) + x(2) = 3 + 2 = 5
x(5) = x(4) + x(3) = 5 + 3 = 8
x(6) = x(5) + x(4) = 8 + 5 = 13
x(7) = x(6) + x(5) = 13+ 8 = 21
x(8) = x(7) + x(6) = 21 + 13 = 34
x(9) = x(8) + x(7) = 34 + 21 = 55
x(10) = x(9) + x(8) = 55 + 34 = 89
x(11) = 89 + 55 = 144
x(12) = 144 + 89 = 233
In the following integral, the contour C encloses the points 2πj and –2πj . The value of the integral
The region specified by in cylindrical coordinates has volume of –––––.
The Laplace transform of the causal periodic square wave of period T shown in the figure below
is
A network consisting of a finite number of linear resistor (R), inductor (L), and capacitor (C)
elements, connected all in series or all in parallel, is excited with a source of the form
The source has nonzero impedance. Which one of the
following is a possible form of the output measured across a resistor in the network?
Consider a series RLCCircuit with voltage source
Here
A firstorder lowpass filter of time constant T is excited with different input signals (with zero
initial conditions up to t = 0 ). Match the excitation signals X,Y, Z with the corresponding time
responses for t 0:
X: Impulse P: 1 – e^{t/T}
Y: Unit step Q: t – T(1 – e^{t/T})
Z: Ramp R: e^{t/T}
An AC voltage source V = 10 sin (t) volts is applied to the following network. Assume that
R1 = 3 k?, R2 = 6k? and R3 = 9k?, and that the diode is ideal.
Rms current I_{rms} (in mA) through the diode is _____
We can join nodes that are at same Potential so network becomes
In the circuit shown in the figure, the maximum power (in watt) delivered to the resistor R is ––––.
Consider the signal x[n] =6δ[n +2] +3δ[n +1]+8δ[n]+7δ[n – 1] +4δ[n – 2].
If X(e^{jω}) is the discretetime Fourier transform of x[n], then
Plancheral’s relation is
Consider a silicon pn junction with a uniform acceptor doping concentration of 1017 cm3 on the pside
and a uniform donor doping concentration of 1016 cm3 on the nside. No external voltage is
applied to the diode. Given:
and q= 1.6 x 10^{19}c
The charge per unit junction area (nC cm^{2}) in the depletion region on the pside is –––––.
Consider an nchannel metal oxide semiconductor field effect transistor (MOSFET) with a gatetosource
voltage of 1.8V. Assume that W /L =4, μ_{N}C_{ox} = 70 X10^{6}AV^{2}, the threshold voltage is 0.3V,
and the channel length modulation parameter is 0.09 V^{1}, In the saturation region, the drain
conductance (in micro siemens)is –––––.
The figure below shows the doping distribution in a Ptype semiconductor in log scale.
The magnitude of the electric field (in kV/cm) in the semiconductor due to non uniform doping is
Consider a silicon sample at T = 300 K, with a uniform donor density N_{d} = 5x1016 cm^{3}
illuminated uniformly such that the optical generation rate is G_{opt} = 1.5 x10^{20} cm^{3}s^{1} through out
the sample. The incident radiation is turned off at t = 0. Assume lowlevel injection to be valid and
ignore surface effects. The carrier lifetimes are _{po} = 0.1 and _{no} = 0.5 ?s.
The hole concentration at t = 0 and the hole concentration at t = 0.3 μs, respectively, are
An ideal opamp has voltage source V_{1}, V_{2}, V_{3}, V_{5}, …. , V_{N–1} connected to the noninverting input
and V_{2}, V_{4}, V_{6} ….V_{N} connected to the inverting input as shown in the figure below (+V_{CC }= 15
volt, –V_{CC} = –15 volt). The voltage V_{1}, V_{2}, V_{3}, V_{5}, V_{6} …. are 1, –1/2, 1/3,–1/4, 1/5, –1/6, …..
volt, respectively. As N approaches infinity, the output voltage (in volt) is ________
A pin photo diode of responsivity 0.8A/W is connected to the inverting input of an ideal opamp
as shown in the figure, +Vcc = 15V, –Vcc = –15V,Load resistor RL = 10 k?. If 10μW
of power is incident on the photodiode, then the value of the photocurrent (in μA) through the
load is _____.
The photo diode with Responsivity 0.8A/W
Diode current = 0.8A/W[10μW]
= 8 x 10^{6}A
V_{0} = –8μ (1M) = –8V
Therefore the value of photo current throughput the load is –800 μA
Identify the circuit below.
(No Answer) if considering OP_{6} → IP_{5}, OP_{7} →IP_{4}
Thus it is a Binary to Gray code converter
The functionally implemented by the circuit below is
Hence it is a “4 to 1 multiplexer”
In a 8085 system, a PUSH operation requires more clock cycles than a POP operation, which one
of the following options is the correct reason for this?
Push takes 12T states due to pre decrement and pop takes 10T states.
The openloop transfer function of a unityfeedback control system is
The value of K at the breakaway point of the feedback control system’s rootlocus plot is ____
Break away point dk/ds=0
The openloop transfer function of a unityfeedback control system is given by
For the peak overshoot of the closedloop system to a until step input to be 10% , the value of K is
The transfer function of a linear time invariant systems is given by H(s) = 2s^{4}–5s^{3}+5s–2
The number of zeros in the right half of the splane is _____.
TF H(s) 2s^{4} – 5s^{3}+5s–2
RH – Criteria
3 Sign Changes
3 Roots (Zeros) in the RH SPlane.
Consider a discreet memoryless source with alphabet S = {s0, s1, s2, s3, s4 …..} and respective
probabilities of occurrence
The entropy of the source (in bits ) is _____.
A digital communication system uses a repetition code for channel encoding/decoding. During
transmission, each bit is repeated three times (0 is transmitted as 000, and 1 is transmitted as 111).
It is assumed that the source puts out symbols independently and with equal probability . The
decoder operates as follows: In a block of three received bits, if the number of zeros exceeds the
number of ones, the decoder decides in favor of a 0, and if the number of ones exceeds the number
of zeros, the decoder decides in favor of a 1,Assuming a binary symmetric channel with crossover
probability p = 0.1, the average probability of error is ________.
P_{e} = P^{3} + 3P^{2} (1 –P)
P = 0.1
P_{e} = (0.1)^{3} + 3 x (0.1)^{2} (1–0.1) = 0.001 + 3 x 0.01 x 0.9 = 0.001 + 0.027 = 0.028
An analog pulse s(t) is transmitted over an additive white Gaussian (AWGN) channel. The
received signal is r(t) = s(t) + n(t), where n(t) is additive white Gaussian noise with power spectral
density N_{0}/2 . The received signal is passed through a filter with impulse response h(t). Let E_{s} and
En denote the energies of the pulse s(t) and the filter h(t), respectively. When the signaltonoise
ratio (SNR) is maximized at the output of the filter (SNR_{max}), which of the following holds?
The impulse response of the filter is same on the signal so E_{s} = E_{h}
The current density in a medium is given by
The total current and the average current density flowing through the portion of a spherical
surface are given, respectively, by
correct option is not given
current passing through the portion of sphere of radius r = 0.8 m is given by
The average current density through the given sphere surface is
An antenna pointing in a certain direction has a noise temperature of 50K. The ambient
temperature is 290K. The antenna is connected to preamplifier that has a noise figure of 2dB and
an available gain of 40 dB over an effective bandwidth of 12 MHz. The effective input noise
temperature Te for the amplifier and the noise power Pao at the output of the preamplifier,
respectively, are
Two lossless Xband horn antennas are separated by a distance of 200?. The amplitude reflection
coefficients at the terminals of the transmitting and receiving antennas are 0.15 and 0.18,
respectively. The maximum directivities of the transmitting and receiving antennas (over the
isotropic antenna) are 18dB and 22dB, respectively. Assuming that the input power in the lossless
transmission line connected to the antenna is 2 W, and that the antennas are perfectly aligned and
polarization matched, the power (in mW) delivered to the load at the receiver is ____
Given
Lossless horn antennas
ηT = ηR = 1
Power Gain = Directivity
Directivity of Txing antenna, DT = 18 dB
10 logD_{T} = 18
GT (or) D_{T} = 63.09
Directivity of Rxing antenna, D_{R} = 22 dB
10logD_{R} = 22
GR(or) D_{R} = 158.48
input power Pin = 2 W
Spacing, r = 200 λ
= 3.1 x10^{–3}
As there is a reflection at the terminals of Rxing antenna power delivered to the load in given by
The electric filed of a uniform plane wave travelling along the negative z direction is given by the
following equation:
This wave is incident upon a receiving antenna placed at the origin and whose radiated electric
field towards the incident wave is given by the following equation:
The polarization of the incident wave, the polarization of the antenna and losses due to the
polarization mismatch are, respectively,
Given
As a tip of electric field intensity is tracing a circle when time varies, hence the wave is said to be circularly polarized in clockwise direction (or) RHCP. Polarizing vector of incident wave is given
by,
As both x & y components are inphase, hence the wave is said to be linear polarized. Polarizing vector of radiated field is
polarizing mismatch; The polarizing mismatch is said to
have, if the polarization of receiving antenna is not same on the polarization of the incident wave.
The polarization loss factor (PLF) characterizes the loss of EM power due to polarization mismatch.
The farzone power density radiated by a helical antenna is approximated as:
The radiated power density is symmetrical with respect to ? and exists only in the upper
hemisphere: is a constant. The power radiated by the antenna (in watts)
and the maximum directivity of the antenna, respectively, are
Given
Power density radiated by the antenna
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