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GATE IN 2026: Instrumentation Engineering

  • Paper code: IN
  • Language: English
  • 46 pages
GATE IN 2026 question paper, GATE 2026, Instrumentation Engineering, page 1 of 46
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Instrumentation Engineering (IN)



General Aptitude (GA)
Q.1 – Q.5 Carry ONE mark Each

 Q.1         Suresh said, “I did it yesterday.”

             Which one of the following options is the correct form of this sentence in indirect
             speech?




 (A)         Suresh said that I did it yesterday.


 (B)         Suresh says I did it yesterday.


 (C)         Suresh says that he did it the day before.


 (D)         Suresh said that he had done it the day before.




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 Q.2         To continue the sequence of tiles shown, the tile indicated by the question mark
             should be




 (A)




 (B)




 (C)




 (D)




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Instrumentation Engineering (IN)




 Q.3         Consider an art gallery whose walkways are shown as lines in the diagram. A
             black dot represents a junction of two walkways. A guard may be placed at a
             junction to watch over the walkways that join at that junction. The minimum
             number of guards needed to watch all the walkways is ________.




 (A)         2


 (B)         3


 (C)         4


 (D)         5




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 Q.4         The 2nd of June is a Thursday in a certain year. Which day of the week is the
             3rd of July in that year?




 (A)         Thursday


 (B)         Friday


 (C)         Saturday


 (D)         Sunday




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 Q.5         A coin with heads facing up is shown as       and a coin with tails facing up is
             shown as         .

             Six coins are placed in the Starting Arrangement, as shown in the figure below.
             A “step” is defined as interchanging a pair of adjacent coins without flipping
             them. The minimum number of steps needed to go from the Starting Arrangement
             to the Final Arrangement, as shown in the figure, is ________.




 (A)         3


 (B)         6


 (C)         9


 (D)         12




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Q.6 – Q.10 Carry TWO marks Each

 Q.6         Exacerbate : Mitigate :: ___________

             Choose the option with the correct pair of words to fill the blank.




 (A)         Aggravate : Alleviate


 (B)         Alleviate : Precipitate


 (C)         Aggravate : Precipitate


 (D)         Emancipate : Exonerate




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 Q.7         A paper shown in Panel I is folded along the dashed lines (- - -) to construct a
             cube. The shaded regions shown in Panel I appear on the outer surface of the cube.
             Referring to cubes shown in Panel II, which one of the options is correct?




 (A)         Only (i) can correspond to the unfolded cube in Panel I.


 (B)         Only (ii) can correspond to the unfolded cube in Panel I.


 (C)         Both (i) and (ii) can correspond to the unfolded cube in Panel I.


 (D)         Neither (i) nor (ii) can correspond to the unfolded cube in Panel I.




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 Q.8         In a population, patients who have high cholesterol also have high blood-pressure
             (BP). Some patients with high BP also have diabetes. There are no patients who
             have both high cholesterol and diabetes. Furthermore,

                  1.    the total number of patients with at least one of these conditions is 75,
                  2.    the number of patients with high cholesterol is 10,
                  3.    the number of patients with high BP is 45, and
                  4.    the number of patients with only high BP and no other conditions is 20.

             Then the number of patients who have both diabetes and high BP is _______




 (A)         0


 (B)         15


 (C)         20


 (D)         10




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 Q.9         Four people P, Q, R, and S, of different ages, make the following observations.

             P – I am younger than S.

             Q – I am neither the youngest nor the oldest.

             R – P is older than me.

             Based on these observations, the youngest person is ______.




 (A)         P


 (B)         Q


 (C)         R


 (D)         S




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 Q.10        Circles C1 , C2 , and C3 , with centers O1, O2, and O3 , and radii r1 , r2 , and r3 ,
             respectively, touch each other as shown in the following figure. Given r1 = 2 cm,
             r2 = 1 cm and the angle ∠O1 O3 O2 is 90°, r3 = _____ cm.




 (A)         1
               (−3 + √17 )
             2

 (B)         1
               (3 + √17 )
             2

 (C)         1
               (−2 + √17 )
             2

 (D)         1
               (−3 + 2√17 )
             2




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Q.11 – Q.35 Carry ONE mark Each

 Q.11        A matrix P ∈ ℝ3×3 satisfies P3 − 4P2 + 5P − 2I = 0 where I is a 3 × 3 identity
             matrix.

             The set of all possible eigenvalues of matrix P is ___.




 (A)         {1,2,3}


 (B)         {1}


 (C)         {1,2}


 (D)         {2}




 Q.12        Which one among the following statements is true for the function f(x) = x|x| ?




 (A)         f(x) is discontinuous but not differentiable at x = 0.


 (B)         f(x) is discontinuous and differentiable at x = 0.


 (C)         f(x) is continuous but not differentiable at x = 0.


 (D)         f(x) is continuous and differentiable at x = 0.




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 Q.13        Consider a function f(z) = z 2 + z + 1 where z ∈ ℂ is a complex variable. A
             simple closed contour γ in z-plane encloses the point z = 1 + 0j.

                                     f(z)
             The value of integral ∮γ z−1 dz = _______.




 (A)         6πj


 (B)         3πj


 (C)         12πj


 (D)         πj




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 Q.14        Consider a matrix

                                                 1 0 2
                                            A = [−1 1 0]
                                                 0 1 2
                      1           x1
             Let b = [3] and x = [x2 ]
                      0           x3

             The number of solutions to the linear system of equations Ax = b is _____.




 (A)         0


 (B)         1


 (C)         6


 (D)         infinitely many




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 Q.15        An electric field has a potential of V(x, y, z) = √x 2 + y 2 + z 2 V.

             A charge of 1 coulomb placed at (î + ĵ + k̂) experiences a force of

                                F⃗ = (aî + bĵ + ck̂) N

             The values of (a, b, c) are ______.




 (A)                 1           1          1
             a=          ,b =        ,c =
                    √3          √3          √3

 (B)            1    1     1
             a = ,b = ,c =
                3    3     3

 (C)                                  1
             a = 0, b = 1, c =
                                      √3


 (D)                                  1
             a = 0, b = 1, c =
                                      3




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 Q.16        The RLC filter shown below acts as a ________.

                        R
                          L
                 Vin                 Vout
                          C




 (A)         low pass filter


 (B)         high pass filter


 (C)         band pass filter


 (D)         band stop filter




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 Q.17        A single phase step-down transformer has a high voltage primary winding and a
             low voltage secondary winding. The secondary winding is connected to a load
             impedance Z2. The impedance Z2 when referred to the primary winding is denoted
             by Z2′ . Which of the following conditions is true?




 (A)         Z2′ = Z2


 (B)         0.5 Z2 < Z2′ < Z2


 (C)         Z2′ > Z2


 (D)         Z2′ ≤ 0.5 Z2




 Q.18        A square wave signal of frequency 20 kHz is passed through an ideal low-pass filter
             with cut-off frequency of 21 kHz. The output signal is a _______.




 (A)         20 kHz sine wave


 (B)         20 kHz square wave


 (C)         20 kHz triangular wave


 (D)         20 kHz saw-tooth wave




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 Q.19        Given x(t) = 4 sin(15π t) + 7 cos(4π t), where t is in seconds.

             The fundamental period of x(t) is _____ seconds.




 (A)         15


 (B)         60


 (C)         30


 (D)         2




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 Q.20        Among the following, the differential equation(s) not representative of a linear
             dynamical system is/are ____.

                             d2x            dx
                  (i)                + 2t        + x(t) = u(t)
                             dt 2           dt

                               dx 2            dx
                  (ii)       ( dt ) + 2 dt + x(t) = u(t)

                             d2x          dx
                  (iii)              +2        + x(t) = u(t)
                             dt 2         dt




 (A)         (i) and (ii) only


 (B)         (i) only


 (C)         (ii) only


 (D)         (ii) and (iii) only




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 Q.21        A common gate amplifier represents a _____________.




 (A)         voltage controlled voltage source


 (B)         current controlled current source


 (C)         voltage controlled current source


 (D)         current controlled voltage source




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 Q.22        In the circuit shown, the BJT has a  of 100. The base-emitter junction voltage is
             0.65 V. The quiescent collector current, IC is _______ mA.


                         5V
              5 kW                   5 kW
                                     IC

              5 kW               5 kW




 (A)         0.365


 (B)         0.435


 (C)         0.625


 (D)         0.862




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 Q.23        The maximum signal to quantization noise ratio (SQNR) for a 16-bit analog-to-
             digital converter is approximately _________ dB.




 (A)         48


 (B)         68


 (C)         88


 (D)         98




 Q.24        The Kelvin double bridge is used to measure ______ valued resistances and has
             ______ resistors in its construction.




 (A)         low ; three-terminal


 (B)         low ; four-terminal


 (C)         high ; three-terminal


 (D)         high ; four-terminal




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 Q.25        Active strain gauges are connected in a half-bridge configuration to measure strain
             in a cantilever element. When powered by a voltage source of 10 V, the voltage at
             the output of the bridge is 1 mV. If the gauge factor is 2.5, the strain in the cantilever
             element is ________ microstrain.




 (A)         40


 (B)         80


 (C)         20


 (D)         160




 Q.26        A glass pH electrode behaves linearly with an output change of 60 mV per unit
             change in pH. The measurement reference is set such that a solution of pH 6
             produces an output of 60 mV. The pH of a solution that results in an output of
             −90 mV is _______ .




 (A)         3.5


 (B)         3


 (C)         8


 (D)         8.5




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 Q.27        An analog speech signal contains signals from 200 Hz to 2400 Hz. It is sampled at
             6 kHz and quantized with 512 levels for pulse code modulation (PCM). The bit rate
             will be _____ kbps.




 (A)         16


 (B)         48


 (C)         19.2


 (D)         54




 Q.28        The slope efficiency of a laser diode is 0.5 W/A, and the output optical power at a
             current of 100 mA is 30 mW. Assuming piece-wise linear characteristics of the laser
             diode, the threshold current of the laser is ________ mA.




 (A)         0


 (B)         20


 (C)         40


 (D)         60




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 Q.29        In a linear element, the measured current is 100 mA ± 2.5% and the measured
             voltage is 5 V ± 5%. Which of the following options show(s) the consumed power?




 (A)         (500 ± 37.5) mW


 (B)         (500 ± 12.5) mW


 (C)         500 mW ± 7.5%


 (D)         500 mW ± 2.5%




 Q.30        Which of the following statements is/are correct for a thermocouple?




 (A)         It is based on the Seebeck Effect.


 (B)         The change in resistance is measured.


 (C)         The voltage difference between the two junctions is linearly proportional to the
             temperature difference between the junctions.


 (D)         It is based on the concept of Joule Heating.




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 Q.31        A data set is given to be [1, 2, 0, −1, −3, 1, 2, 0, 1].

             The median of the data set is ____. (rounded off to the nearest integer)


 Q.32        The potential difference between nodes A and B in a circuit is vA − vB = 5 V. The
             work done in moving a charge of 1 coulomb from point B to A is ____ J. (answer
             in integer)


 Q.33        In a series RL circuit shown in the figure, the current through the resistor lags the
             AC source voltage by 45°. Let R = 100π Ω and L = 2 H.


                                     R

                                         L

             The frequency of the source is ____ Hz. (rounded off to the nearest integer)


 Q.34        In the circuit below the maximum value of vout is ________ V. (rounded off to the

             nearest integer)


                                         4W

               15 cos wt                     3V          vout
                                           8W


 Q.35        The minimum number of comparators required in a 6-bit flash analog-to-digital
             converter is ________. (answer in integer)




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Q.36 – Q.65 Carry TWO marks Each

 Q.36        A box contains three apples and two oranges. Two fruits are removed randomly in
             succession. The probability that the first is an apple and the second is an orange
             is _____ .




 (A)         3
             5

 (B)          3
             20

 (C)          3
             10

 (D)         2
             5




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 Q.37        An electric field in free space is

             E⃗⃗ = (2x + 5y + 6z)î + (5x + 4y + 10z)ĵ + (6x + 10y + 2z)k̂ V/m.

             The charge density is ____ C/m3. (ε0 is the permittivity of free space)




 (A)         8ε0


 (B)         10ε0


 (C)         6ε0


 (D)         4ε0




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 Q.38        A straight thin wire carrying a current of I = 1 A in the direction

                         1            2           1
              n̂ =           î +          ĵ +        k̂ is placed inside a magnetic field of B⃗⃗ = (2î + 2k̂) T.
                      √6              √6          √6
             The force per unit length on the wire is _____ N/m.




 (A)         2√6î − 2√6k̂


 (B)
              3      3      3
             √ î − √ ĵ + √ k̂
              2      4      4


 (C)          4              4
                  î −           k̂
             √6          √6


 (D)
              3      3      3
             √ î + √ ĵ + √ k̂
              2      4      4




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 Q.39        A two-port network has z-parameters z11 = z22 = 10 W, and z12 = z21 = 5 W.

             The value of RL such that maximum power is transferred to RL is _________ W.


                             5W
               5V                       z11 z12
                                        z21 z22                  RL




 (A)         5.67


 (B)         8.33


 (C)         10.33


 (D)         25.67




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 Q.40        In the circuit shown below, the value of the output voltage V0 is _____ V.

                                     1W    1W

               2W             2W     2W       2W
                                                            V0
                                     4V       4V




 (A)         2


 (B)         3


 (C)         4


 (D)         8




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 Q.41        A signal x(t ) is shown below.




             The plot of y(t )  1  x(4  t ) is shown in ______.




   (A)




   (B)




   (C)




   (D)




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 Q.42        In the table shown below, List-I are the system responses to input x(t) and List-II
             are the system properties. The correct matching is ____.


                                 List-I                             List-II


                             (M)     x 2 (t )        (I) Linear and Time-invariant


                             (N)     x(t )          (II) Non-linear and Time-varying


                             (O) | x(3  t ) |       (III) Linear and Time-varying


                             (P)     x(t  3)        (IV) Non-linear and Time-invariant




 (A)         M-IV, N-III, O-II, P-I


 (B)         M-II, N-I, O-IV, P-III


 (C)         M-III, N-IV, O-II, P-I


 (D)         M-I, N-IV, O-III, P-II




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 Q.43        Given two signals: x(t) = u(t − 2) − u(t − 3), and y(t) = e −4t u(t).

             If z(t) = x(t) ∗ y(t), then Z(s) is _______.




 (A)         e −3s [e s − 1]
                s(s + 4)


 (B)         e −s [e −3s − 1]
             (s + 3)(s + 4)


 (C)          e −3s [1 − e s ]
             (s + 3)(s + 4)


 (D)         e −3s [1 − e s ]
                s(s + 4)




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 Q.44        A linear time invariant (LTI) system is described by:

                                       ẋ      0       1 x1      1
                                      [ 1] = [           ][ ] + [ ]u
                                       ẋ 2   −10      −7 x2     1
                                                         x1
                                              y = [1 1] [x ]
                                                          2

             The poles of the system are ____.




 (A)         −2, −5


 (B)         2, 5


 (C)         −2, 5


 (D)         2, − 5




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 Q.45        In the circuit shown below, R is 1 kW and Rf is 10 kW. If Vin is 100 mV and the
             op-amps have supply voltages of ±15 V, then Vout is _______ V.




                                         Rf
                Vin                  R              Vout
                                         Rf




 (A)         −15


 (B)         15


 (C)         2.1


 (D)         1.1




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 Q.46        In the following active filter circuit with ideal op-amps, R is 1 kW, C is 1 F, and
             Vin has an amplitude of 1 V at 1000 rad/s.

             The amplitude of Vout is __________ V.


                                                         R

                                     R                       C                R
                          R          C       R                       R
               Vin
                                                                                          Vout




 (A)         0.5


 (B)         0.707


 (C)         1.0


 (D)         1.414




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 Q.47        The initial state of Q3Q2Q1Q0 in the digital circuit shown below is 1011.

             The new value of Q3Q2Q1Q0 after two rising edges of the clock (CLK) will be
             _____.




                                     D3   Q3    D2     Q2      D1   Q1         D0    Q0


                                      CLK         CLK           CLK             CLK

              CLK




 (A)         1101


 (B)         0101


 (C)         1010


 (D)         1011




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 Q.48        A closed Lissajous pattern observed on an oscilloscope in the X − Y mode has three
             horizontal tangencies and two vertical tangencies in steady state. If the signal-
             frequency on channel-X is 600 Hz, then the signal-frequency on channel-Y
             is ___________ Hz.




 (A)         300


 (B)         400


 (C)         600


 (D)         900




 Q.49        If the definition of SI unit ‘X’ is required to define SI unit ‘Y’, the dependency is
             indicated as X  Y. A valid order of dependencies, as per present convention,
             is ___________.




 (A)         metre  second  kilogram  kelvin


 (B)         second  metre  kilogram  kelvin


 (C)         metre  second  kelvin  kilogram


 (D)         second  kilogram  kelvin  metre




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 Q.50        A parallel plate capacitive displacement sensor has a plate area of 2 cm2. The air
             gap between the plates is decreased by 0.1 mm from an initial value of 0.5 mm. The
             percentage change in the capacitance value is ______ %.

             (Assume permittivity as ε0 = 8.854 × 10−12 F/m)




 (A)         10.0


 (B)         14.1


 (C)         25.0


 (D)         30.0




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 Q.51        The emitted radiant energy from a piece of metal was measured using a pyrometer.
             The temperature was calculated to be 1000 °C, assuming a surface emissivity of
             0.8. It was later found that the true surface emissivity was 0.7.

             The actual temperature of the object is nearest to ______ °C.




 (A)         1043


 (B)         958


 (C)         1033


 (D)         967




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 Q.52        An amplitude modulated voltage signal x(t) drives a load of 1 W.

             x(t) = K cos(300π t) + L cos(240π t) + L cos(360π t).

             If the efficiency is 60% and the carrier power is 50 W, the value of L is ______ V.




 (A)         8.66


 (B)         1.22


 (C)         0.81


 (D)         17.32




 Q.53        Given f(x, y) = x 2 − 2xy + y 2

             The complete contour of the equation f(x, y) = 1 is described by the option(s) ___.




 (A)         A line, x − y = 1


 (B)         A circle with radius 1


 (C)         An ellipse with length of major axis equal to 1


 (D)         A line, x − y = −1




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 Q.54                                             d2 x
             Given a differential equation dt 2 + x = 0 with x(0) ≠ 0.


             Which of the following statements is/are true?




 (A)                        dx(t) 2
             |x(t)|2 + |             | = 0 for all t ≥ 0
                              dt



 (B)                        dx(t) 2
             |x(t)|2 + |             | = c for all t ≥ 0, for some real constant c > 0
                              dt



 (C)                        dx(t) 2
             |x(t)|2 + |             | = ejt for all t ≥ 0
                              dt



 (D)                        dx(t) 2
             |x(t)|2 + |             | = sin t for all t ≥ 0
                              dt




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 Q.55        Which of the following functions represent(s) the output of the CMOS logic-gate
             shown in the circuit below?

                                VDD


                                          C
                  A                   B
                            f




 (A)           ̅+̅
             f=A B ⋅ C̅


 (B)         f = ̅̅̅̅̅̅̅̅
                 A+BC


 (C)            ̅ ⋅ (B
             f= A    ̅ + C̅)


 (D)         f = ̅̅̅̅̅̅̅̅̅̅̅̅̅̅
                 A ⋅ (B + C)




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 Q.56        A 16-bit processor has 16-bit wide instructions and a few internal registers. Every
             16-bit instruction is encoded in a fixed format with one operation code of 7 bits and
             up to three operands. The operand can be an internal register and each operand is
             encoded by 3 bits. All the internal registers can be specified in an instruction using
             three bits.

             The correct statement(s) for this processor is/are _____.




 (A)         The processor has 16 internal registers.


 (B)         The processor can support 128 unique operation codes (Opcodes).


 (C)         The processor has up to 8 internal registers.


 (D)         The processor can support 512 unique operation codes (Opcodes).




 Q.57                      1,    t ∈ [0,2]
             Let f(t) = {−t + 3, t ∈ [2,3]
                           0, otherwise

             Then

               ∞
             ∫−∞ f(τ)dτ =_____. (rounded off to one decimal place)




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 Q.58        A single phase transformer has a rating of 10 kVA, 50 Hz, 1100 V/ 220 V. In an
             open circuit test with the high voltage side open, the following are obtained:

                       Voltage applied to the low voltage winding = 220 V
                       Measured power = 363 W
                       Measured current = 2.75 A

             Magnetizing reactance Xm referred to the high voltage winding is __________Ω.
             (rounded off to the nearest integer)


 Q.59        A linear time invariant (LTI) system has a transfer function

                                                        10(s + 1)
                                            G(s) =
                                                      s(s 2 + 2s + 5)

             The system is placed in unity negative feedback configuration.

             For a unit ramp reference, the steady state error is _______.

             (rounded off to two decimal places)


 Q.60                                    K
             The system G (s) =               has a gain margin of 20 dB. The value of K
                                       (s+1)4
             is ______. (rounded off to two decimal places)


 Q.61        In the phase-locked-loop circuit shown below, the output of the VCO is a digital
             square wave.


               Input          ÷20 counter         Phase         Loop        VCO        Output
                                                 detector       filter

                                                      ÷1024 counter

             If the input is a square wave at 10 kHz, the steady state frequency of the output
             is ________ kHz. (rounded off to the nearest integer)




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 Q.62        A digital counter increments its count every 0.1 s. The counter is used in an
             instrument to measure frequency. The counter is operated for one period of the input
             signal to the instrument to measure its frequency. The input signal is approximately
             at 100 kHz. The maximum error in the measured frequency is _____ kHz.
             (rounded off to the nearest integer)


 Q.63        A current carrying semiconductor of thickness 0.7 mm is placed in a transverse
             magnetic field. The measured Hall voltage is 0.9 mV and the current is 6 mA. If
             the Hall coefficient is 4 x 10-4 m3/C, the value of the incident magnetic field
             is _______ T. (rounded off to two decimal places)


 Q.64        For a fiber Bragg grating-based sensor, the shift in the Bragg wavelength gives
             information about the value of the measurand. For a Bragg wavelength of 1550 nm
             and effective index of 1.44, the grating period is _______ nm.

             (rounded off to two decimal places)


 Q.65        A photodiode has a responsivity 0.8 A/W. If the input optical power to the
             photodiode is 2 mW, the power delivered to a 50 W load is _______ W.

             (rounded off to the nearest integer)




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Source: GATE. Question paper published by GATE.