Engineering Entrance Sample Papers

GATE EC sample paper

gate ec question paper

Questions carrying One Mark Each

Question: The minimum number of equations required to analyze the circuit shown in

(a) 3
(b) 4
(c) 6
(d) 7
Ans: (b)

Question: The rank of the matrix

(a) 0
(b) 1
(c) 2
(d) 3
Ans: (c)

Question:

, where P is a vector, is equal to

(a) (b) (c) (d)

Ans. (d)

Question: A probability density function is of the form

The value of K is
(a) 0.5
(b) 1
(c) 0.5alpha symbol
(d) alpha symbol
Ans: (c)

Question: The concentration of minority carriers in an extrinsic semiconductor under equilibrium is:
(a) directly proportional to the doping concentration
(b) inversely proportional to the doping concentration
(c) directly proportional to the intrinsic concentration
(d) inversely proportional to the intrinsic concentration
Ans: (b)

Question: Under low level injection assumption, the injected minority carrier current for an extrinsic semiconductor is essentially the
(a) diffusion current
(b) drift current
(c) recombination current
(d) induced current
Ans: (a)

Question: The phenomenon known as “Early Effect” in a bipolar transistor refers to a reduction of the effective base-width caused by
(a) electron-hole recombination at the base
(b) the reverse biasing of the base-collector junction
(c) the forward biasing of emitter-base junction
(d) the early removal of stored base charge during saturation-to-cutoff switching
Ans: (b)

Question: The number of product terms in the minimized sum-of-product expression obtained through the following K-map is (where “d” denotes don’t care states)

(a) 2
(b) 3
(c) 4
(d) 5
Ans: (a)

Question: The Dirac delta function delta symbol (t ) is defined as

(a) (b)
(c) (d)

Ans. (d)

Question: The open-loop transfer function of a unity-gain feedback control system is given by

The gain margin of the system in dB is given by
(a) 0
(b) 1
(c) 20
(d) infinite symbol

Question: In the system shown below, x (t ) = (sint )u (t ). In steady-state, the response y (t )will be:

(a) (b) (c) (d) sin t – cos t

Ans. (a)

Question: The electric field of an electromagnetic wave propagating in the positive z direction is given by

The wave is
(a) linearly polarized in the z-direction
(b) elliptically polarized
(c) left-hand circularly polarized
(d) right-hand circularly polarized
Ans: (c)

Related: GATE Electronics and Communication Engineering (ESE) Syllabus

Question: A transmission line is feeding 1 Watt of power to a horn antenna having a gain of 10 dB. The antenna is matched to the transmission line. The total power radiated by the horn antenna into the free-space is:
(a) 10 Watt
(b) 1 Watt
(c) 0.1 Watt
(d) 0.01 Watt
Ans: (a)

Question: A source of angular frequency 1 rad/sec has a source impedance consisting of 1 resistance in series with 1 H inductance. The load that will obtain the maximum power transfer is
(a) 1 resistance
(b) 1 resistance in parallel with 1 H inductance
(c) 1 resistance in series with 1 F capacitor
(d) 1 resistance in parallel with 1 F capacitor
Ans: (c)

Question: A series RLC circuit has a resonance frequency of 1 kHz and a quality factor Q = 100. If each R, L and C is doubled from its original value, the new Q of the circuit is
(a) 25
(b) 50
(c) 100
(d) 200
Ans: (b)

Question: The Laplace transform of i(t) is given by(s)=2/s(1+s)
As t , the value of i(t) tends to
(a) 0
(b) 1
(c) 2
(d)

Question: The differential equation for the current i(t) in the circuit of Figure is

(a) (b)
(c) (d)

Ans. (c)

Question: n-type silicon is obtained by doping silicon with
(a) Germanium
(b) Aluminum
(c) Boron
(d) Phosphorus
Ans: (d)

Question: Choose proper substitutes for X and Y to make the following statement correct Tunnel diode and Avalanche photodiode are operated in X bias and Y bias respectively.
(a) X : reverse, Y : reverse
(b) X : reverse, Y : forward
(c) X : forward, Y: reverse
(d) X : forward, Y : forward
Ans: (c)

Question: For an n-channel enhancement type MOSFET, if the source is connected at a higher potential than that of the bulk (i.e. VSB > 0), the threshold voltage VT of the MOSFET will
(a) remain unchanged
(b) decrease
(c) change polarity
(d) increase
Ans: (a)

Question 21: Choose the correct match for input resistance of various amplifier configurations shown below.

Configuration                            Input resistance

CB: Common Base                         LO :Low

CC: Common Collector                 MO:Moderate

CE: Common Emitter                   HI : High

(a) CB-LO, CC-MO, CE-HI
(b) CB-LO, CC-HI, CE-MO
(c) CB-MO, CC-HI, CE-LO
(d) CB-HI, CC-LO, CE-MO
Ans: (b)

Question: The circuit shown in figure is best described as a

(a) bridge rectifier
(b) ring modulator
(c) frequency discriminatory
(d) voltage doubler
Ans: (d)

Question 23: If the input to the ideal comparator shown in figure is a sinusoidal signal of 8V (peak to peak) without any DC component, then the output of the comparator has a duty cycle of

(a) 1/2
(b) 1/3
(c) 1/6
(d) q/12

Ans. (b)

Question: The output of the 74 series of TTL gates is taken from a BJT in
(a) totem pole and common collector configuration
(b) either totem pole or open collector configuration
(c) common base configuration
(d) common collector configuration
Ans: (b)

Question: Without any additional circuitry, an 8:1 MUX can be used to obtain
(a) some but not all Boolean functions of 3 variables
(b) all function of 3 variables but none of 4 variables
(c) all functions of 3 variables and some but not all of 4 variables
(d) all functions of 4 variables
Ans: (b)

Questions carrying Two Marks Each

Question: A transmission line of characteristic impedance 50W is terminated in a load impedance ZL. The VSWR of the line is measured as 5 and the first of the voltage maxima in the line is observed at a distance of /4 from the load. The value of ZL is

(a) 10
(b) 250
(c) (19.23 + j46.15)
(d) (19.23 – 46.15)

Question: The output of a 3-stage Johnson (twisted ring) counter is fed to a digital-to-analog (D/A) converter as shown in the figure below. Assume all the states of the counter to be unset initially. The waveform which represents the D/A converter output Vo is

(a) (b)
(c) (d)

Ans. (a)

Question: Two D flip-flops are connected as a synchronous counter that goes through the following QB QA sequence 00 arrow sign 11 arrow sign 01 arrow sign 10 arrow sign 00 arrow sign

(a) (b)
(c) (d)

Ans. (d)

Question: In the circuit shown below, the current I is equal to

(a) 14 0ºA
(b) 2.0 0ºA
(c) 2.8 0ºA
(d) 3.2 0ºA
Ans: (b)

Question: A numerical solution of the equation f (x) = x + x + 3 = 0 can be obtained using Newton- Raphson method. If the starting value is x = 2 for the iteration, the value of x that is to be used in the next step is
(a) 0.306
(b) 0.739
(c) 1.694
(d) 2.306
Ans: (c)

Question: A 0 to 6 counter consists of 3 flip flops and a combination circuit of 2 input gate(s). The combination circuit consists of
(a) one AND gate
(b) one OR gate
(c) one AND gate and one OR gate
(d) two AND gate
Ans: (d)

Question: An 8085 assembly language program is given below. Assume that the carry flag is initially unset. The content of the accumulator after the execution of the program is

(a) 8CH
(b) 64H
(c) 23H
(d) 15H
Ans: (c)

Question: The first six points of the 8-point DFT of a real valued sequence are5, 1 – j3, 0, 3 – j4, 0 and 3 + j4. . The last two points of the DFT are respectively
(a) 0, 1 – j3
(b) 0, 1 + j3
(c) 1 + j3, 5
(d) 1 – j3, 5
Ans: (c)

Question 34:

In the circuit below, the network N is described by the following

(a) 1/90
(b) –1/90
(c) –1/99
(d) –1/11
Ans: (d)

Question: A fair dice is tossed two times. The probability that the second toss results in a value that is higher than the first toss is
(a) 2/36
(b) 2/6
(c) 5/12
(d) 1/2
Ans: (c)

Question: The value of the integral

(a) 1
(b)
(c) 2
(d) 2

Ans: (a)

Question:

The derivative of the symmetric function drawn in figure will look like

(a) (b)
(c) (d)

Ans. (c)

Question:

Match the following and choose the correct combination:

Group 1                                                 Group 2

E. Newton –Raphson method                 1. Solving nonlinear equations

F. Runge-Kutta method                          2. Solving linear simultaneous equations

G. Simpson’s Rule                                  3. Solving ordinary differential equations

H. Gauss elimination                               4. Numerical integration

5. Interpolation

6. Calculation of Eigen values
(a) E – 6 F – 1 G – 5 H – 3
(b) E – 1 F – 6 G – 4 H – 3
(c) E – 1 F – 3 G – 4 H – 2
(d) E – 5 F – 3 G – 4 H – 1
Ans: (c)

Question: For the circuit in figure the instantaneous current i1 (t) is

(a) (b) (c) 560 Amps (d) 5 – 60 Amps

Ans. (a)

Question: For the circuit shown in figure, Thevenin’s voltage and Thevenin’s equivalent resistance at terminals a – b is

(a) 5 V and 2
(b) 7.5 V and 2.5
(c) 4 V and 2
(d) 3 V and 2.5

Ans: (b)

Question:

The h parameters of the circuit shown in figure are

(a) (b) (c) (d)

Ans. (d)

Question: For an n-channel MOSFET and its transfer curve shown in figure, the threshold voltage is

(a) 1 V and the device is in active region.
(b) -1 V and the device is in saturation region.
(c) 1 V and the device is in saturation region.
(d) -1 V and the device is in active region.
Ans: (c)

Question: The Zener diode in the regulator circuit shown in figure has a Zener voltage of 5.8 Volts and a Zener knee current of 0.5 mA. The maximum load current drawn from this circuit ensuring proper functioning over the input voltage range between 20 and 30 Volts, is

(a) 23.7 mA
(b) 14.2 mA
(c) 13.7 mA
(d) 24.2 mA
Ans: (d)

Question: The output y(t) of a linear time invariant system is related to its input x(t) by the following equation: y(t) = 0.5 x (t – td + T) + x (t – td) + 0.5x (t – td – T). The filter transfer function H (omega symbol) of such a system is given by

(a) (b) (c) (d)

Ans. (a)

Question: For a signal x(t) the Fourier transform is X(f). Then the inverse Fourier transform of X (3f + 2) is given by

(a) (b) (c) (d) x (3t + 2)

Ans. (b)

Question: In the circuit shown below, the initial charge on the capacitor is 2.5 mC, with the voltage polarity as indicated. The switch is closed at time t=0. The current i(t) at a time t after the switch is closed is

(a) (b)
(c) (d)

Ans. (c)

Question: Figure shows the Nyquist plot of the open-loop transfer function G(s)H(s) of a system. If G(s)H(s) has one right hand pole, the closed loop system is

(a) always stable
(b) unstable with one closed loop right hand pole
(c) unstable with two closed loop right hand poles
(d) unstable with three closed loop right hand poles
Ans: (a)

Common Data Questions

The system under consideration is an RC low-pass filter (RC-LPF) with R = 1.0 komega symbol and C = 1.0µF.

Question:

(a) 327.8
(b) 163.9
(c) 52.2
(d) 104.4
Ans: (c)

Question: Let tg(f) be the group delay function of the given RC-LPF and f2 = 100 Hz. Then tg(f2) in ms, is
(a) 0.717
(b) 7.17
(c) 71.7
(d) 4.505
Ans: (b)

Common Data Questions

The input-output transfer function of a plant H(s) = 100/s(s + 10). The plant is placed in a unity negative feedback configuration as shown in the figure below.

Question: The gain margin of the system under closed loop unity negative feedback is
(a) 0dB
(b) 20dB
(c) 26 dB
(d) 46 dB
Ans: (c)

Related: GATE CS paper

Question: The signal flow graph that DOES NOT model the plant transfer function H(s) is

(a) (b)
(c) (d)

Ans. (c)

Linked Answer Questions carrying Two Marks Each

Consider an 8085-microprocessor system.

Question: The following program starts at location 0100H.
LXI SP, 00FF
LXI H, 0701
MVI A, 20H
SUB M

The content of accumulator when the program counter reaches 0109H is
(a) 20H
(b) 02H
(c) 00H
(d) FFH
Ans: (a)

Question: If in addition following code exists from 0109H onwards.
ORI 40H
ADD M
What will be the result in the accumulator after the last instruction is executed?
(a) 40H
(b) 20H
(c) 60H
(d) 42H
Ans: (c)

Statement for Linked Answer Questions

A four-phase and an eight-phase signal constellation are shown in the figure below.

Question: For the constraint that the minimum distance between pairs of signal points be d for both constellations, the radii r1, and r2 of the circles are
(a) r1 = 0.707d, r2 = 2.782d
(b)  r1 = 0.707d, r2 = 1.932d
(c)  r1 = 0.707d, r2 = 1.545d
(d) r1 = 0.707d, r2 = 1.307d
Ans: (d)

Question: Assuming high SNR and that all signals are equally probable, the additional average transmitted signal energy required by the 8-PSK signal to achieve the same error probability as the 4-PSK signal is
(a) 11.90 dB
(b) 8.73 dB
(c) 6.79 dB
(d) 5.33 dB
Ans: (d)

Questions carrying One Mark Each

Question: There are two candidates P and Q in an election. During the campaign, 40% of the voters promised to vote for P, and rest for Q. However, on the day of election 15% of the voters went back on their promise to vote for P and instead voted for Q. 25% of the voters went back on their promise to vote for Q and instead voted for P. Suppose, P lost by 2 votes, then what was the total number of voters?
(a) 100
(b) 110
(c) 90
(d) 95
Ans; (a)

Question: Choose the word from the options given below that is most nearly opposite in meaning to the given word:
Frequency
(a) periodicity
(b) rarity
(c) gradualness
(d) persistency
Ans: (b)

Question: Choose the most appropriate word from the options given below to complete the following sentence: Under ethical guidelines recently adopted by the Indian Medical Association, human genes are to be manipulated only to correct diseases for which _____ treatments are unsatisfactory.
(a) Similar
(b) Most
(c) Uncommon
(d) Available
Ans: (d)

Question: The question below consists of a pair of related words followed by four pairs of words. Select the pair that best expresses the relation in the original pair:
Gladiator : Arena
(a) dancer : stage
(b) commuter: train
(c) teacher : classroom
(d) lawyer : courtroom
Ans: (d)

Question: Choose the most appropriate word from the options given below to complete the following sentence:

It was her view that the country’s problems had been ______ by foreign technocrats, so that to invite them to come back would be counter-productive.
(a) Identified
(b) ascertained
(c) Texacerbated
(d) Analysed
Ans: (c)

Questions carrying Two Marks Each

Question: Three friends, R, S and T shared toffee from a bowl. R took 1/3rd of the toffees, but returned four to the bowl. S took 1/4th of what was left but returned three toffees to the bowl. T took half of the remainder but returned two back into the bowl. If the bowl had 17 toffees left, how many toffees-were originally there in the bowl?
(a) 38
(b) 31
(c) 48
(d) 41
Ans: (c)

Question: Exports from Three Companies Over the Years (in Rs. crore)

For which of the following pairs of years the total exports from the three Companies together are equal?
(a) 1995 and 1998
(b) 1996 and 1998
(c) 1997 and 1998
(d) 1995 and 1996
Ans: (d)

Question: Given that f(y) = | y | / y, and q is any non-zero real number, the value of | f(q) – f(–q) | is
(a) 0
(b) -1
(c) 1
(d) 2
Ans: (d)

Question: The sum of n terms of the series 4 + 44 + 444 + …. is

Ans. (c)

Question: The horse has played a little known but very important role in the field of medicine. Horses were injected with toxins of diseases until their blood built up immunities. Then a serum was made from their blood. Serums to fight with diphtheria and tetanus were developed this way. It can be inferred from the passage that horses were
(a) given immunity to diseases
(b) generally quite immune to diseases
(c) given medicines to fight toxins
(d) given diphtheria and tetanus serums
Ans: (b)

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Vishal Arora

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