The GATE Grind

GATE 2020 IN – Previous Year Questions with Solutions

All 65 questions of GATE 2020 IN with answers and explanations. Read each question, then practise it by topic or as a full paper.

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  1. Question 1 (1 mark, Multiple choice) – He is known for his unscrupulous ways. He always sheds tears to deceive people.
  2. Question 2 (1 mark, Multiple choice) – Jofra Archer, the England fast bowler, is than accurate.
  3. Question 3 (1 mark, Multiple choice) – Select the word that fits the analogy: Build : Building :: Grow : .
  4. Question 4 (1 mark, Multiple choice) – “I do not think you know the case well enough to have opinions. Having said that, I agree with your other point.” What does “having said that” mean in…
  5. Question 5 (1 mark, Multiple choice) – Define [x] as the greatest integer less than or equal to x, for each x(-,). If y=[x], find the area under y for x[1,4].
  6. Question 6 (2 marks, Multiple choice) – Crowd funding deals with mobilisation of funds for a project from a large number of people, who would be willing to invest smaller amounts through…
  7. Question 7 (2 marks, Multiple choice) – P, Q, R and S are to be uniquely coded using and . If P is coded and Q is coded , then R and S, respectively, can be coded as .
  8. Question 8 (2 marks, Multiple choice) – Find the sum of the first n terms in the sequence 8, 88, 888, 8888, ….
  9. Question 9 (2 marks, Multiple choice) – Select the graph that schematically represents BOTH y=xm and y=x1/m properly in 0 x1, for integral m > 1. The choices are arranged A, B in the top row…
  10. Question 10 (2 marks, Multiple choice) – The bar graph shows students who appeared and passed in an examination for schools P, Q, R and S. Find the average success rate (percentage) of the…
  11. Question 11 (1 mark, Multiple choice) – Unit vectors along the mutually perpendicular x,y,z axes are i, j, k. Two vectors a,b lie in z = 0 and satisfy a b for every scalar α. A vector…
  12. Question 12 (1 mark, Multiple choice) – The recursion is X n+1=X n-h[F(X n)-X n], with X 0=1 and small positive h. It numerically solves which ODE?
  13. Question 13 (1 mark, Multiple choice) – In Ax=b, A is a real 24 matrix and b0. Can multiplying by AT and inverting ATA always give a unique x?
  14. Question 14 (1 mark, Multiple choice) – The series circuit shown has resistors rated 100 Ω, 1 W; 2 Ω, 0.5 W; and 1 Ω, 0.25 W. Find the safe maximum current I.
  15. Question 15 (1 mark, Multiple choice) – A differentiator has a transfer function whose
  16. Question 16 (1 mark, Multiple choice) – A phase-lead network has G(s)=(1+0.2s)/(1+0.05s). Its maximum phase shift occurs at angular frequency
  17. Question 17 (1 mark, Multiple choice) – The circuit has ideal diodes, a 5 V Zener breakdown voltage, a 10 sin(100πt) V input through 50 Ω, and a 100 Ω branch to a +5 V source as shown. The…
  18. Question 18 (1 mark, Multiple choice) – Let f(A,B,C,D)= m(0,1,2,6,8,9,10,11)+ d(3,7,14,15), where m denotes minterms and d don’t-cares. The minimal sum-of-products expression is
  19. Question 19 (1 mark, Multiple choice) – A Q meter is best suited to measure the
  20. Question 20 (1 mark, Multiple choice) – A Hall sensor carries current I and has perpendicular magnetic flux density B. Its Hall voltage is
  21. Question 21 (1 mark, Multiple choice) – Choose the Boolean expression represented by the shaded Venn regions in the figure.
  22. Question 22 (1 mark, Multiple choice) – For the shown 4:1 multiplexer with select bits S 1 (MSB) and S 0 (LSB), the output O is
  23. Question 23 (1 mark, Multiple choice) – For x[n]=(2 n)u[n], where u[n]=1 for n=0,1,2, and 0 otherwise, the period is
  24. Question 24 (1 mark, Multiple choice) – A closed-loop system has C(s)/R(s)=1/(s+1). For input r(t)= t, its steady-state output is
  25. Question 25 (1 mark, Multiple choice) – For f(z)=1/(z+a) with a > 0, evaluate Cf(z)dz counterclockwise on any circle of radius R > 0 centred at (−a,0).
  26. Question 26 (1 mark, Numerical answer) – A player scores a basket with probability 0.1 on each independent attempt. On two attempts, find the probability of scoring only on the second, to two…
  27. Question 27 (1 mark, Numerical answer) – With both op-amps ideal, find output V₁ in volts in the circuit shown.
  28. Question 28 (1 mark, Numerical answer) – Three 400 Ω resistors form a delta supplied by balanced 400 V RMS, 50 Hz, R-Y-B three-phase three-wire mains. Find line current in A, to one decimal…
  29. Question 29 (1 mark, Numerical answer) – For x(t)=e- t and X(j)= - x(t)e-j tdt, find X(j0).
  30. Question 30 (1 mark, Numerical answer) – A second-order system has closed-loop poles s=-3 j4. Find the time of the first maximum of its unit-step response, in seconds, to two decimal places.
  31. Question 31 (1 mark, Numerical answer) – The ideal-op-amp circuit shown has an 8 kΩ feedback resistor to the positive input, and a 1 kΩ/2 kΩ divider to its negative input. Find V x/I x in kΩ.
  32. Question 32 (1 mark, Numerical answer) – A 10 kHz sinusoid is sampled at 15 k samples/s. The sampled signal passes through an ideal low-pass filter with 25 kHz cutoff. Find the maximum output…
  33. Question 33 (1 mark, Numerical answer) – A 200 mV full-scale dual-slope ADC uses 100 mV reference and a fixed first-integration time of 100 ms. In continuous-conversion mode, find the minimum…
  34. Question 34 (1 mark, Numerical answer) – A capacitive sensor has C x=(1000x) pF and is excited by 10(100 t) V. It drives a high-input-impedance amplifier through a grounded shielded cable…
  35. Question 35 (1 mark, Numerical answer) – Two 100 Ω resistors of tolerances 3% and 4% are connected in series. Find effective combination tolerance in percent, to one decimal place.
  36. Question 36 (2 marks, Multiple choice) – For M=pmatrix1&-1&0\\1&-2&1\\0&-1&1pmatrix, which is an eigenvector?
  37. Question 37 (2 marks, Multiple choice) – The ODE is dx/dt= x, with x(0) = 0. Its solution is
  38. Question 38 (2 marks, Multiple choice) – A straight line intercepts the x-axis at −0.5 and y-axis at 1. Its equation is
  39. Question 39 (2 marks, Multiple choice) – A negative-feedback system has loop transfer function G(s)H(s)=1/[s(s-2)]. Its Nyquist plot
  40. Question 40 (2 marks, Multiple choice) – For mesh currents I₁,I₂,I₃ and source polarities in the circuit shown, which matrix equation is correct?
  41. Question 41 (2 marks, Numerical answer) – Find the minimum of f(x,y)=x2+y2 on x+y=1, to one decimal place.
  42. Question 42 (2 marks, Numerical answer) – Two equally likely bags each contain 10 balls. B1 has 7 red and 3 green; B2 has 3 red and 7 green. A randomly drawn ball is red. Find the probability…
  43. Question 43 (2 marks, Numerical answer) – The series circuit shown has R = 100 Ω, L = 100 mH, C = 10 μF and source 1002(1000t) V. Find the RMS current in A.
  44. Question 44 (2 marks, Numerical answer) – A balanced 400 V line-voltage three-phase supply feeds the shown unbalanced star: 300 Ω from each line to a floating star point, with an extra 100 Ω…
  45. Question 45 (2 marks, Numerical answer) – Let g[n]=1 for n = 0 and zero otherwise, and h[n]=1 for n = 0,3,6,9,… and zero otherwise. If y[n]=h[n] g[n] with convolution denoted by ⊗, find y[2].
  46. Question 46 (2 marks, Numerical answer) – A negative-feedback system has G(s)H(s)=K/[s(s+2)(s+6)], K > 0. Find K at the root-locus breakaway point, to one decimal place.
  47. Question 47 (2 marks, Numerical answer) – The negative unity-feedback system shown has forward path K/( s+1) with K,τ positive. Its response to r(t)=10u(t) tends to 8. Find K.
  48. Question 48 (2 marks, Numerical answer) – The ideal-op-amp precision-rectifier circuit shown is driven by 2(5000 t) V. Find the reading in volts of its 1 Hz bandwidth PMMC voltmeter.
  49. Question 49 (2 marks, Numerical answer) – In the shown circuit both op-amps are ideal and Vₓ = 0.5 mV. Find the steady-state output Vₒ in V, to two decimal places.
  50. Question 50 (2 marks, Numerical answer) – Two T flip-flops are connected as shown. Initially A = B = 1. Input x takes values 1,0,1 in the next three clock cycles. Find the decimal value of…
  51. Question 51 (2 marks, Numerical answer) – A 10-bit DAC has 1.023 V full-scale output. Its address inputs A 9 A 2 connect to an 8-bit microprocessor’s D 7 D 0, while A 1,A 0 are grounded. If…
  52. Question 52 (2 marks, Numerical answer) – A balanced three-phase load on 400 V, 50 Hz, three-wire RYB mains is measured by two wattmeters. W₁ is in line R, W₂ in line B. Line current is 1/3 A.…
  53. Question 53 (2 marks, Numerical answer) – A 6½-digit timer-counter is in time-period mode with range set to ns. It displays 1000000. With the same input, it is changed to frequency mode with…
  54. Question 54 (2 marks, Numerical answer) – The charge-amplifier circuit shown uses an ideal op-amp powered by VCC = 5 V and biased at VCC/2. A piezoelectric sensor generates q p=0.1(10000 t)…
  55. Question 55 (2 marks, Numerical answer) – A metallic strain gauge has gauge factor 2 and unstressed resistance 1 kΩ. It is bonded to material with elastic modulus 200 GN/m² and forms a quarter…
  56. Question 56 (2 marks, Numerical answer) – A 10 mm diameter laser beam is focused onto an optical fibre by a thin biconvex lens of refractive index 1.5. Fibre core and cladding indices are 1.55…
  57. Question 57 (2 marks, Numerical answer) – A slab of refractive index 1.5 and thickness t is surrounded by air on both sides. Light of free-space wavelength 600 nm is incident normally. Find…
  58. Question 58 (2 marks, Numerical answer) – The finite sequence is X = (1,1,1). Its inverse DFT is x = (x(0),x(1),x(2)). Find x(2).
  59. Question 59 (2 marks, Numerical answer) – The capacitor network, DC source and amplifier of gain G = −5 are shown. Find effective capacitance between A and B in μF, to two decimal places.
  60. Question 60 (2 marks, Numerical answer) – A state model is x 1=x 2, x 2=-6x 1-5x 2, with x 1(0)=0,x 2(0)=1. Find x₂(1), to two decimal places.
  61. Question 61 (2 marks, Numerical answer) – Assume all diodes in the circuit are ideal. Find current Iₖ through the 3 kΩ resistor in mA, to one decimal place.
  62. Question 62 (2 marks, Numerical answer) – A 1000/1 A, 5 VA, unity-power-factor current transformer has 1000 secondary turns. At primary current 1000 A, ratio error is −0.1% and phase error is…
  63. Question 63 (2 marks, Numerical answer) – An LVDT has mutual inductances M₁,M₂ to its two secondary coils. Their self-inductances remain constant with displacement x. At x = 0, M₁ = M₂ = M₀.…
  64. Question 64 (2 marks, Numerical answer) – The Maxwell–Wien bridge shown balances when C₁ = 100 nF and R₁ = 100 kΩ. Its excitation is √2 cos(1000t) V. Find the coil Q factor.
  65. Question 65 (2 marks, Numerical answer) – A negative-feedback system has G(s)H(s)=2(s+1)/s2. Find phase margin in degrees, to one decimal place.