2015| SET 2 - (ECE GATE Exam) - Previous Question Paper Solution

Description: GATE Exam Previous Year Question Paper Solution Electronics and Communication (ECE) - 2015 (SET 2)
Number of Questions: 37
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Tags: Verbal Ability Numerical Ability Engineering Mathematics Electronics Devices Electronics and Communication Semiconductors Feedback Control System Counter and Registers Transfer Function Electromagnetic Wave Logic Gate and Related Devices Circuits Z Transform
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Directions: Carry One Mark Each.

Which of the following is an adverb?

  1. Misogynousness

  2. Misogynity

  3. Misogynously

  4. Misogynous


Correct Option: C
Explanation:

Correct Answer: Misogynously

Directions: Carry One Mark Each.

Choose the word that is most similar in meaning to the given word:

Awkward

  1. Inept

  2. Graceful

  3. Suitable

  4. Dreadful


Correct Option: A
Explanation:

Correct Answer: Inept

Directions: Carry One Mark Each.

If a2 + b2 + c2 = 1, then ab + bc + ac lies in the interval

  1. $\bigg[1, \frac{2}{3} \bigg]$

  2. $\bigg[\frac{-1}{2} , 1\bigg]$

  3. $\bigg[-1, \frac{1}{2} \bigg]$

  4. [2, –4]


Correct Option: B
Explanation:

Directions: Carry One Mark Each.

Ram and Ramesh appeared in an interview for two vacancies in the same department. The probability of Ram’s selection is $\frac{1}{6}$ and that of Ramesh's selection is $\frac{1}{8}$. What is the probability that only one of them will be selected?

  1. $\frac{47}{48}$

  2. $\frac{1}{4}$

  3. $\frac{13}{48}$

  4. $\frac{35}{48}$


Correct Option: B
Explanation:

Directions: Carry One Mark Each.

In the following sentence, certain parts are underlined and marked P, Q and R. One of the parts may contain certain error or may not be acceptable in standard written communication. Select the part containing an error. Choose (4) as your answer if there is no error.

The student corrected $\frac{\text{all the errors}}{P}$ that $\frac{\text{the instructor marked}}{Q}$ on the $\frac{\text{answer book}}{R}$.

  1. P

  2. Q

  3. R

  4. No error


Correct Option: B
Explanation:

In part Q, the is not required.

Directions: Carry Two Marks Each.

Lamenting the gradual sidelining of arts in school curricula, a group of prominent artists wrote to the Chief Minister last year, asking him to allocate more funds to support arts education in schools. However, no such increase has been announced in this year’s budget. The artists expressed their deep anguish at their request not being approved, but many of them remain optimistic about funds coming in the future.

Which of the following statements are logically valid and can be inferred from the above statements?

I. The artists expected funding for arts to increase this year. II. The Chief Minister was receptive to the idea of increasing funding for arts. III. The Chief Minister is a prominent artist. IV. Schools are giving less importance to arts education nowadays.

  1. III and IV

  2. I and IV

  3. II, III and IV

  4. I and III


Correct Option: B
Explanation:

Correct Answer: I and IV

Directions: Carry Two Marks Each.

Given below are two statements followed by two conclusions. Assuming these statements to be true, decide which conclusion(s) logically follow(s).

Statements: All film stars are playback singers. All film directors are film stars. Conclusions: I. All film directors are playback singers. II. Some film stars are film directors.

  1. Only conclusion I follows

  2. Only conclusion II follows

  3. Neither conclusion I nor II follows

  4. Both conclusions I and II follow


Correct Option: D
Explanation:

Directions: Carry One Mark Each.

Choose the appropriate word/phrase out of the four options given below to complete the following sentence.

Dhoni, as well as the other team members of the Indian team, _________ present on the occasion.

  1. were

  2. was

  3. has

  4. have


Correct Option: B
Explanation:

Here, the focus of sentence is on Dhoni, not team members. Because the team phrase can be omitted from the sentence, it will be was and not were.

Directions: Carry One Mark Each.

The electric field of a uniform plane electromagnetic wave is

$\overrightarrow{E} = (\overrightarrow{a_z} + j4 \overrightarrow{a_y})exp[j(2 \pi \times 10^7 t - 0.2z)]$

The polarization of the wave is

  1. right handed circular

  2. right handed elliptical

  3. left handed circular

  4. left handed elliptical


Correct Option: D
Explanation:

Directions: Carry One Mark Each.

By performing cascading and/or summing/differencing operations using transfer function blocks G1(s) and G2(s), one cannot realise a transfer function of the form

  1. G1(s)G2(s)

  2. $\frac{G_1(s)}{G_2(s)}$

  3. G1(s)$\bigg( \frac{1}{G_1(s)} + G_2(s) \bigg)$

  4. G1(s)$\bigg( \frac{1}{G_1(s)} - G_2(s) \bigg)$


Correct Option: B
Explanation:

Division of two transfer functions cannot be performed by performing cascading and/or summing/differencing operations.

Directions: Carry One Mark Each.

An electric bus has on-board instruments that report the total electricity consumed since the start of the trip as well as the total distance covered. During a single day of operation, the bus travels on stretches M, N, O and P, in that order. The cumulative distance travelled and the corresponding electricity consumption are shown in the table below. Stretch| Cumulative distance (km)| Electricity used (kWh) | | M| 20|12| | N| 45| 25| | O| 75| 45| | P| 100| 57|

Which of the following is the stretch where the electricity consumption per km is the minimum?

  1. M

  2. N

  3. O

  4. P


Correct Option: D
Explanation:

In the figure shown, the output Y is required to be Y = AB + $\overline{CD}$.

The gates G1 and G2 must respectively be

  1. NOR and OR

  2. OR and NAND

  3. NAND and OR

  4. AND and NAND


Correct Option: A
Explanation:

Directions: Carry One Mark Each.

Let the signal f(t) = 0 be outside the intervals T1 and T2, where T1 and T2 are finite. Furthermore, |f(t)| < $\infty$. The region of convergence (ROC) of the signal’s bilateral Laplace transform F(s) is

  1. a parallel strip containing the j$\Omega$ axis

  2. a parallel strip not containing the j$\Omega$ axis

  3. the entire s-plane

  4. a half plane containing the j$\Omega$ axis


Correct Option: C
Explanation:

Directions: Carry One Mark Each.

The bilateral Laplace transform of a function , is

  1. $\frac{a-b}{s}$

  2. $\frac{e^2(a -b)}{I^S}$

  3. $\frac{e^{-as}- e^{-bs}}{s}$

  4. $\frac{e^{s(a - b)}}{s}$


Correct Option: C
Explanation:

Directions: Carry One Mark Each.

The value of x for which all the eigen values of the matrix given below are real is

$\begin{bmatrix} \ 10 & 5+j & 4 \ \ x & 20 & 2 \ \ 4 & 2 & -10 \ \end{bmatrix}$

  1. 5 + j

  2. 5 – j

  3. 1 – 5j

  4. 1 + 5j


Correct Option: B
Explanation:

Directions: Carry One Mark Each.

The general solution of the differential equation $\frac{dy}{dx} = \frac{1 + cos 2y}{1 - cos 2x}$ is

  1. tan y – cos x = c (c is a constant)

  2. tan x – cot y = c (c is a constant)

  3. tan y + cot x = c (c is a constant)

  4. tan x + cot y = c (c is a constant)


Correct Option: C
Explanation:

Directions: Carry One Mark Each.

The 2-port admittance matrix of the circuit shown is given by

  1. $\begin{bmatrix} \ 0.3 & 0.2 \ \ 0.2 & 0.3 \ \end{bmatrix}$

  2. $\begin{bmatrix} \ 15 & 5 \ \ 5 & 15 \ \end{bmatrix}$

  3. $\begin{bmatrix} \ 3.33 & 5 \ \ 5 & 3.33 \ \end{bmatrix}$

  4. $\begin{bmatrix} \ 0.3 & 0.4 \ \ 0.4 & 0.3 \ \end{bmatrix}$


Correct Option: A
Explanation:

Directions: Carry One Mark Each.

The magnitude and phase of the complex Fourier series coefficients ak of a periodic signal x(t) are shown in the figure. Choose the correct answer from the given options.

Notation: C is the set of complex numbers, R is the set of purely real numbers and P is the set of purely imaginary numbers.

  1. x(t) $\epsilon$ R

  2. x(t) $\epsilon$ P

  3. x(t) $\epsilon$ (C – R)

  4. The information given is not sufficient to draw any conclusion about x(t).


Correct Option: A
Explanation:

As the magnitude spectrum is even, the corresponding time-domain signal is a real signal.

Directions: Carry One Mark Each.

In an 8085 microprocessor, which of the following instructions change(s) the content of the accumulator?

  1. MOV B and M

  2. PCHL

  3. RNZ

  4. SBI BE (H)


Correct Option: D
Explanation:

SBI BE (H) This instruction subtracts the immediate data from the accumulator and stores the result in it. So, the accumulator is affected.

Directions: Carry One Mark Each.

If the circuit shown has to function as a clamping circuit, which one of the following conditions should be satisfied for sinusoidal signal of period T?

  1. RC << T

  2. RC = 0.35 T

  3. RC $\approx$ T

  4. RC >> T


Correct Option: D
Explanation:

$\text{Time constant = $\tau$ = RC} \\ \text{If} \hspace{0.5cm} RC >> T = \text{period of sinusoid} \\ \text{Then the capacitor will not play its role and clamping will take place.}$

Directions: Carry One Mark Each.

For the signal flow graph shown in the figure, the value of $\frac{C(s)}{R(s)}$ is

  1. $\frac{1}{1 - G_1G_2H_1 - G_3G_4H_2 - G_2G_3H_3 + G_1G_2G_3G_4H_1H_2}$

  2. $\frac{G_1G_2G_3G_4}{1 + G_1G_2H_1 + G_3G_4H_2 + G_2G_3H_3 + G_1G_2G_3G_4H_1H_2}$

  3. $\frac{1}{1 + G_1G_2H_1 + G_3G_4H_2 + G_2G_3H_3 + G_1G_2G_3G_4H_1H_2}$

  4. $\frac{1}{1 - G_1G_2H_1 - G_3G_4H_2 - G_2G_3H_3 + G_1G_2G_3G_4H_1H_2}$


Correct Option: B
Explanation:

Directions: Carry Two Marks Each.

Let X $\epsilon$ P{0, 1} and Y $\epsilon$ {0, 1} be two independent binary random variables. If P(X = 0) = p and P(Y = 0) = q, then P(X + Y $\geq$ 1) is equal to

  1. pq + (1 – p) (1 – q)

  2. pq

  3. p(1 – q)

  4. 1 – pq


Correct Option: D
Explanation:

Directions: Carry Two Marks Each.

An LC tank circuit consists of an ideal capacitor C that is connected in parallel with a coil of inductance L having an internal resistance R. The resonant frequency of the tank circuit is

  1. $\frac{1}{2 \pi \sqrt{LC}}$

  2. $\frac{1}{2 \pi \sqrt{LC}}\sqrt{1 - R^2 \frac{C}{L}}$

  3. $\frac{1}{2 \pi \sqrt{LC}}\sqrt{1 - \frac{L}{R^2 C}}$

  4. $\frac{1}{2 \pi \sqrt{LC}}\sqrt{1 - R^2 \frac{C}{L}}$


Correct Option: B
Explanation:

Directions: Carry Two Marks Each.

The figure shows a binary counter with synchronous clear input. With the decoding logic shown, the counter works as a

  1. mod-2 counter

  2. mod-4 counter

  3. mod-5 counter

  4. mod-6 counter


Correct Option: C
Explanation:

Directions: Carry Two Marks Each.

The state variable representation of a system is given as

The response y(t) is

  1. sin (t)

  2. 1 - et

  3. 1 - cos(t)

  4. 0


Correct Option: D
Explanation:

Directions: Carry Two Marks Each.

is an independent and identically distributed (i, i, d) random process with Xn equally likely to be +1 or –1. is another random process obtained as Yn = Xn + 0.5 Xn – 1. The autocorrelation function of is another random process obtained as Yn = Xn + 0.5 Xn – 1. The autocorrelation function of denoted by Ry[k] is


Correct Option: B
Explanation:

Directions: Carry Two Marks Each.

Consider the differential equation $\frac{ds}{dt}$ = 10 – 0.2x with initial condition x(0) = 1. The response x(t) for t > 0 is

  1. 2 – e–0.2t

  2. 2 – e0.2t

  3. 50 – 49e–0.2t

  4. 50 – 49e0.2t


Correct Option: C
Explanation:

Directions: Carry Two Marks Each.

Input x(t) and output y(t) of an LTI system are related by the differentiation equation y’’(t) – y’(t) – 6y(t) = x(t). If the system is neither casual nor stable, the impulse response h(t) of the system is

  1. $ \frac{1}{5}e^{3t}u(-t*) +\frac{1}{5}e^{-2t}u(-t)$

  2. $- \frac{1}{5}e^{3t}u(-t) +\frac{1}{5}e^{-2t}u(-t)$

  3. $\frac{1}{5}e^{3t}u^*(-t) -\frac{1}{5}e^{-2t}u(t)$

  4. $- \frac{1}{5}e^{3t}u(-t) -\frac{1}{5}e^{-2t}u(t)$


Correct Option: B
Explanation:

Directions: Carry Two Marks Each.

A zero mean white Gaussian noise having power spectral density of $\frac{N_o}{2}$ is passed through an LTI filter whose impulse response h(t) is shown in the figure. The variance of the filtered noise at t = 4 is

  1. $\frac{3}{2}A^2 N_o$

  2. $\frac{3}{4}A^2 N_o$

  3. A2No

  4. $\frac{1}{2}A^2 N_o$


Correct Option: A
Explanation:

Directions: Carry Two Marks Each.

A function of Boolean variables X, Y and Z is expressed in terms of the minterms as

$F(X, Y, Z) = \sum(1, 2, 5, 6, 7)$

Which of the following products of sums given below is equal to the function F(X, Y, Z)?

  1. $(\bar{X} + \bar{Y}+ \bar{Z}).(\bar{X} + Y + Z).(X + \bar{Y}+\bar{Z})$

  2. $(X + Y + Z).(X + \bar{Y} + \bar{Z}).(\bar{X} + Y + Z)$

  3. $(\bar{X} + \bar{Y} + Z).(\bar{X} + y + \bar{Z}). (X + \bar{Y}+ Z).(X + Y + \bar{Z}).(X + Y + Z)$

  4. $( X + y + \bar{Z}) . (\bar{X} + Y + Z). (\bar{X} + Y + \bar{Z}).(\bar{X} + \bar{Y}+ \bar{Z})$


Correct Option: B
Explanation:

Directions: Carry Two Marks Each.

Consider a binary, digital communication system which uses pulses g(t) and –g(t) for transmitting bits over an AWGN channel. If the receiver uses a matched filter, which of the following pulses will give the minimum probability of bit error?

  1. (A)

  2. (B)

  3. (C)

  4. (D)


Correct Option: A
Explanation:

Directions: Carry Two Marks Each.

A 1-to-8 demultiplexer with data input Din, address inputs S0, S1 and S2 (with S0 as the LSB) and $\overline{y}_o$ to $\overline{y}_7$ as the eight demultiplexed output, is to be designed using two 2 - to - 4 decoders (with enable input $\bar{E}$ and address input A0 and A1). As shown in the figure, Din, S0, S1 and S2 are to be connected to P, Q, R and S, but not necessarily in this order. The respective input connections to P, Q, R and S terminals should be

  1. S2, Din, S0 and S1

  2. S1, Din, S0 and S2

  3. Din, S0, S1 and S2

  4. Din, S2, S0 and S1


Correct Option: D
Explanation:

Directions: Carry Two Marks Each.

The output of a standard second-order system for a unit step input is given as y(t) = 1 – $\frac{2}{\sqrt{3}}$e–t cos$\Big( \sqrt{3t} - \frac{\pi}{6} \Big)$. The transfer function of the system is

  1. $\frac{2}{(s+2)(s + \sqrt{3})}$

  2. $\frac{1}{s^2 + 2s + 1}$

  3. $\frac{3}{s^2 + 2s + 3}$

  4. $\frac{4}{s^2 + 2s + 4}$


Correct Option: D
Explanation:

Directions: Carry Two Marks Each.

The electric field of a plane wave that is propagating in a lossless non-magnetic medium is given by

E(z, t) = ax 5 cos(2$\pi$ x 109 t + $\beta$z) + ay3 cos x (2$\pi$ x 109t + $\beta$z - $\frac{\pi}{2}$)

The polarization is

  1. right hand circular

  2. left hand elliptical

  3. right hand elliptical

  4. linear


Correct Option: B
Explanation:

Directions: Carry Two Marks Each.

The energy band diagram and electron density profile n(x) in a semiconductor are shown in the figure. Assume that n(x) = 105 e$\Big( \frac{q \alpha x}{kT} \Big)$cm–3, with $\alpha$ = 0.1 V/cm and x expressed in cm. Given$\frac{kT}{q}$= 0.026 V, Dn = 36 cm2 s–1, and$\frac{D}{\mu}$=$\frac{kT}{q}$. The electron current density (in A/cm2) at x = 0 is

  1. – 4.4 x 10–2

  2. – 2.2 x 10–2

  3. 0

  4. 2.2 x 10–2


Correct Option: C
Explanation:

Correct Answer: 0

Directions: Carry One Mark Each.

The signal cos(10$\pi$t + $\frac{\pi}{4}$) is ideally sampled at a sampling frequency of 15 Hz. The sampled signal is passed through a filter with impulse response $\bigg( \frac{sin (\pi t)}{\pi t} \bigg)$cos$\bigg( 40 \pi t - \frac{\pi}{2} \bigg)$. The filter output is

  1. $\frac{15}{2}$cos$\bigg( 40 \pi t - \frac{\pi}{4} \bigg)$

  2. $\frac{15}{2}\bigg( \frac{sin (\pi t)}{\pi t} \bigg)cos\bigg( 10 \pi t + \frac{\pi}{4} \bigg)$

  3. $\frac{15}{2}cos\bigg( 10 \pi t - \frac{\pi}{4} \bigg)$

  4. $\frac{15}{2}\bigg( \frac{sin (\pi t)}{\pi t} \bigg)cos\bigg( 10 \pi t - \frac{\pi}{2} \bigg)$


Correct Option: A
Explanation:

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