The GATE Grind

GATE 2014 EC (EC2) – Previous Year Questions with Solutions

All 65 questions of GATE 2014 EC (EC2) 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) – Communication and interpersonal skills are important in their own ways.
  2. Question 2 (1 mark, Multiple choice) – She will feel much better if she .
  3. Question 3 (1 mark, Multiple choice) – She could not the thought of the election to her bitter rival.
  4. Question 4 (1 mark, Multiple choice) – A regular six-sided die is thrown a very large number of times. Observed frequencies are 1:0.167, 2:0.167, 3:0.152, 4:0.166, 5:0.168, 6:0.180. This…
  5. Question 5 (1 mark, Numerical answer) – Fill the missing number: 2, 3, 6, 15, , 157.5, 630.
  6. Question 6 (2 marks, Multiple choice) – Find the odd group of letters.
  7. Question 7 (2 marks, Multiple choice) – Each ladder step has two lights, chosen from red, blue, green and yellow. Whenever a light is red, the other on its step is blue. Whenever one is…
  8. Question 8 (2 marks, Numerical answer) – Eight consecutive odd numbers sum to 656. Four consecutive even numbers average 87. Find the sum of the smallest odd number and second-largest even…
  9. Question 9 (2 marks, Multiple choice) – The pie charts show export quantity shares and export revenue shares by item. Total exports are 500 thousand tonnes, earning ₹250 crore. Which listed…
  10. Question 10 (2 marks, Multiple choice) – A half-full tank empties in 30 minutes at a constant drain rate. Water is pumped in while draining continues. What pumping rate fills it completely in…
  11. Question 11 (1 mark, Numerical answer) – det(A) = 5 and det(B) = 40. Find det(AB).
  12. Question 12 (1 mark, Numerical answer) – X is chosen uniformly from the positive odd integers below 100. Find E[X].
  13. Question 13 (1 mark, Multiple choice) – For 0 t<, where does f(t)=e-t-2e-2t attain its maximum?
  14. Question 14 (1 mark, Multiple choice) – Evaluate x(1+1/x)x.
  15. Question 15 (1 mark, Multiple choice) – The characteristic equation of d2y/dx2+2\,dy/dx+y=0 has equal roots. Find possible .
  16. Question 16 (1 mark, Multiple choice) – Norton’s theorem replaces a complex network connected to a load by an equivalent impedance .
  17. Question 17 (1 mark, Numerical answer) – The ideal switch shown has been open for a long time. It closes at t = 0. Find the magnitude of current through the 4 kΩ resistor at t = 0⁺ (mA).
  18. Question 18 (1 mark, Multiple choice) – A silicon bar has donor doping N D=2.251015 atoms/cm³. At 300 K, n i=1.51010 cm⁻³. Assuming complete ionization, find equilibrium electron and hole…
  19. Question 19 (1 mark, Multiple choice) – Increasing base recombination in a BJT increases .
  20. Question 20 (1 mark, Multiple choice) – Shallow P-well or N-well regions in CMOS technology can be formed using .
  21. Question 21 (1 mark, Multiple choice) – Identify the feedback topology of the amplifier shown. Base-bias circuitry is omitted for simplicity.
  22. Question 22 (1 mark, Multiple choice) – In the differential amplifier shown, common-mode and differential-mode gain magnitudes are A cm and A d. If R E increases, which occurs?
  23. Question 23 (1 mark, Numerical answer) – Two cascaded voltage amplifiers are shown. A1 has open-loop voltage gain 10, input resistance 10 kΩ, output resistance 1 kΩ. A2 has corresponding…
  24. Question 24 (1 mark, Multiple choice) – For an n-variable Boolean function, the maximum number of prime implicants is .
  25. Question 25 (1 mark, Numerical answer) – How many bytes represent decimal 1856357 in packed BCD?
  26. Question 26 (1 mark, Multiple choice) – A half-subtractor has inputs X,Y and difference N = X − Y. Find borrow M and difference N.
  27. Question 27 (1 mark, Multiple choice) – An FIR system has H(z)=1+72z-1+32z-2. Classify it.
  28. Question 28 (1 mark, Multiple choice) – x[n]=x[-n], and X(z) is its z-transform. If 0.5+j0.25 is a zero, which must also be a zero?
  29. Question 29 (1 mark, Numerical answer) – For the periodic square wave shown, find the approximate ratio of power in the seventh harmonic to that in the fifth.
  30. Question 30 (1 mark, Numerical answer) – A second-order system has undamped natural frequency 40 rad/s and damping ratio 0.3. Find damped natural frequency (rad/s).
  31. Question 31 (1 mark, Multiple choice) – For the system shown, find Y(s)/X₂(s) when X₁(s) = 0.
  32. Question 32 (1 mark, Multiple choice) – AWGN capacity is C=W 2(1+P/(2W)) bps, where W is bandwidth, P average received power and 2 one-sided noise PSD. For fixed P/2=1000, find capacity as W…
  33. Question 33 (1 mark, Numerical answer) – In sinusoidal AM without overmodulation, envelope maximum and minimum are 3 V and 1 V. Find modulation index µ.
  34. Question 34 (1 mark, Numerical answer) – The shown lossless transmission line is matched to a resistive load by a λ/4 transformer. Find transformer characteristic impedance (Ω).
  35. Question 35 (1 mark, Multiple choice) – Which TEM field pattern travels in the positive x direction?
  36. Question 36 (2 marks, Multiple choice) – The linear system pmatrix2&1&3\\3&0&1\\1&2&5pmatrixpmatrixa\\pmatrix=pmatrix5\\-4\\14pmatrix has .
  37. Question 37 (2 marks, Multiple choice) – The real part of analytic f(z), z = x + jy, is e-y x. Which is its imaginary part?
  38. Question 38 (2 marks, Numerical answer) – Find the maximum determinant of a real symmetric 2 × 2 matrix with trace 14.
  39. Question 39 (2 marks, Numerical answer) – Let r=x a x+y a y+z a z and r= r . Evaluate div(r2 r).
  40. Question 40 (2 marks, Numerical answer) – A series LCR circuit operates off resonance with current leading supply voltage. Current magnitude is half its resonant value. Given L = 1 H, C = 1 F…
  41. Question 41 (2 marks, Numerical answer) – For the two-port circuit shown, find hybrid parameter h₂₂ (S).
  42. Question 42 (2 marks, Multiple choice) – The capacitor shown is initially uncharged. Find branch current I(t) (mA) for t > 0.
  43. Question 43 (2 marks, Numerical answer) – In the coupled circuit shown, 56% of total flux from one coil links the other. Find mutual inductance (H).
  44. Question 44 (2 marks, Numerical answer) – Given q=1.610-19 C, kT/q=25 mV and n=1000 cm²/(V·s), electrons injected into p-type silicon have concentration gradient 1021 cm⁻⁴. Find…
  45. Question 45 (2 marks, Numerical answer) – The abrupt PN junction shown is at 300 K. N-side depletion width X n=0.2 µm and silicon permittivity si=1.04410-12 F/cm. Find peak junction electric…
  46. Question 46 (2 marks, Multiple choice) – A reverse-biased silicon diode has N A=91016 cm⁻³, N D=1016 cm⁻³ and total depletion width 3 µm. Silicon permittivity is 1.0410-12 F/cm. Find p-side…
  47. Question 47 (2 marks, Multiple choice) – The diode shown has V on = 0.7 V and is otherwise ideal. If Vi = 5 sin(ωt) V, find minimum and maximum Vo (V), respectively.
  48. Question 48 (2 marks, Multiple choice) – The NMOS shown has threshold 0.8 V. Ignore channel length modulation. At drain voltage V D = 1.6 V, I D = 0.5 mA. Adjust R and V DD to obtain V D = 2…
  49. Question 49 (2 marks, Numerical answer) – The MOSFETs shown have V t =2 V and K=12 C ox(W/L)=0.1 mA/V². Find I D (mA).
  50. Question 50 (2 marks, Multiple choice) – For the circuit shown, select the output y timing diagram from W1,W2,W3,W4.
  51. Question 51 (2 marks, Multiple choice) – Both flip-flop outputs Q₁,Q₂ start at 0. Find the sequence generated at Q₁ by the clock.
  52. Question 52 (2 marks, Multiple choice) – The figure shows an 8085 interface for input of eight-bit digital data DI₀–DI₇ from an external device. Which instruction transfers it correctly?
  53. Question 53 (2 marks, Numerical answer) – x[n]=n for 0 n10, and zero otherwise. If y[n] is x[n] convolved with itself, find y[4].
  54. Question 54 (2 marks, Multiple choice) – A causal stable LTI system has y[n]= y[n-1]+ x[n]. Its impulse response satisfies n=0 h[n]=2. Find the relation between ,.
  55. Question 55 (2 marks, Numerical answer) – Evaluate -sinc2(5t)\,dt.
  56. Question 56 (2 marks, Multiple choice) – An unforced LTI system obeys x=pmatrix-1&0\\0&-2pmatrixx. For x 1(0)=1, x 2(0)=-1, find its state response.
  57. Question 57 (2 marks, Numerical answer) – A minimum-phase system has the shown asymptotic Bode magnitude plot. Connected in unity negative feedback, find its closed-loop steady-state error for…
  58. Question 58 (2 marks, Multiple choice) – For the state-space system represented by the signal-flow diagram, which property always holds?
  59. Question 59 (2 marks, Numerical answer) – A one-bit quantizer input X has density f X(x)=2e-2x for x0, and zero otherwise. Find the threshold making the two outputs equiprobable.
  60. Question 60 (2 marks, Multiple choice) – Coherent orthogonal binary FSK sends equiprobable s 1(t)=(2 f 1t) and s 2(t)=(2 f 2t), with =4 mV, through AWGN having two-sided PSD N 0/2=0.510-12…
  61. Question 61 (2 marks, Numerical answer) – A real stationary process X(t) has PSD S X(f)=1/W for f W, and zero otherwise. Find E[ X(t)X(t-1/(4W))].
  62. Question 62 (2 marks, Numerical answer) – The figure gives the message spectrum M(f), with A = 100 Hz and B = 40 Hz. Modulating signals are v(t)=(2 f ct) and w(t)=(2(f c+A)t), with f c>A. Both…
  63. Question 63 (2 marks, Multiple choice) – A plane wave has E(z,t)=3 x( t-kz+30)-4 y( t-kz+45) mV/m. Find its polarization.
  64. Question 64 (2 marks, Numerical answer) – For the transmission line shown, find impedance Zin (Ω) between node A and ground.
  65. Question 65 (2 marks, Numerical answer) – A rectangular waveguide has internal dimensions a × b, a > b. TE₁₁ cutoff is the arithmetic mean of TE₁₀ and TE₂₀ cutoffs. Given a=5 cm, find b (cm).