InterviewSolution
Saved Bookmarks
InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
84 - 2 is equal to |
| Answer» (2A)16 = (00101010)2 2's complement = 11010110 = (D6)16 (84)16 + (D6)16 ⇒ 1(5A)16 carry discarded ⇒ (5A)16 . | |
| 2. |
The transform of a particular signal is given as The practical implementation of the system will be |
| Answer» When get high value at ω = 0, and low value at ω = p, hence we get a low pass filter. So the system is min-phase causal system. For practical implementation of the system, the system has to be stable. | |
| 3. |
If = then G(1/) is __________ where G() |
| Answer» The signal g(t) given above is a gaussian pulse and it satisfies the relation g(t) = - 2pt g(t) ∴ Its fourier transform is same as the signal itself in frequency domain G(f) = e-pf2 G(1/p) = e-p(1/p)2 = e-1/p. | |
| 4. |
Figure shows four D type FFs are connected as a shift register using an XOR gate. The initial state and 3 subsequent states for 3 clock pulses are also givenThe state Q Q Q Q after the 4th clock pulse is |
| Answer» After the 3rd pulse FF3 is 0 and FF4 is 1, so that XOR output is 1 which is fed to DA. So, QA = 1, QA to QB → 0 AB to AC → 0, QC → QD → 0. | |
| 5. |
A rectangular wave guide is designed to propagate at the dominant mode TE at a frequency of 5 GHz. The cut-off frequency is 0.8 of signal frequency. The ratio of the guide width to height is 2. The dimensions of the guide are |
| Answer» λc = 2a or ⇒ a = 3.75 cm Also, ∴ . | |
| 6. |
In the Taylor series expansion of exp() + sin() about the point = , the coefficient of ( - ) is |
| Answer» f(x) = ex + sin x Coefficient of (x - p)2 = 1 / 2! f''(x) f'(x) = ex + cos x f'(x) = ex - sin x f''(x)|x=p = ep Thus coefficient of (x - p)2 = 0.5 . | |
| 7. |
Calculate the electrostatic force of repulsion between two mica particles at a distance of 10 from each other. Charge on a particle is 3.2 x 10 C. (relative permittivity for mica is 5) |
| Answer» By Coulomb's law: Electrostatic force = = = 18.43 x 10- 3 N. | |
| 8. |
What is the propagation constant for air filled wave guide with dimensions = 1.59" and = 0.795" at 4.95 GHz. The wave impedance is |
| Answer» . | |
| 9. |
If (10) x (10) = (100); (100) x (100) = (10000) then can take value |
| Answer» (10)x x (10)x = (100)x ⇒ x x x = x2 (100)x x (100)x = (10000)x x2 x x2 = x4 True for all values of x. | |
| 10. |
A uniform plane wave in air with H = 3 sin (ω - 8)A/ is incident normally on a region with σ = 0, μ = 1, ε = 9. The reflection coefficient is |
| Answer» . | |
| 11. |
A memoryless source emits symbols each with a probability . The entropy of the source as a function of |
| Answer» H = n P log Since they all have same probability. Thus it increases with n. | |
| 12. |
If the intrinsic resistivity at 300°K is 0.37 and the electron and hole mobilities at 300°K are 0.28 and 0.15 /volt-sec, then the intrinsic carrier concentration of Germanium is __________ . |
| Answer» | |
| 13. |
Find 'X' in the circuit below:(A, B, C, D) = Σ(6, 7, 13, 14);(A, B, C, D) = Σ(3, 6, 7);(A, B, C, D) = Σ(5, 6, 7, 14, 15) |
| Answer» f1(A, B, C, D) = ∑(6, 7, 13, 14) f2(A, B, C, D) = ∑(3, 6, 7) f1 ⊕ f2 = ∑(3, 13, 14) f3 x (f1 ⊕ f2) = ∑(14)= Y X = f1 x Y = ∑(14). | |
| 14. |
The transfer characteristic for the precision rectifier circuit shown below is (assume ideal OP-AMP and practical diodes) |
| Answer» When Vi = - 10 V0 = 5. | |
| 15. |
F = ∑(0, 3, 4, 5, 7) = |
| Answer» | |
| 16. |
The matrix A is defined as A = . The eigen values of A are |
| Answer» Since the given matrix is triangular, roots are elements of the principle diagonal. i.e. 1A = - 1, - 3, 2 1A2 = (- l)2, (- 3)2, (2)2 = 1, 9, 4. | |
| 17. |
A uniform plane wave travelling in air is incident on the plane boundary between air and another dielectric medium with e = 15. The reflection coefficient for normal incidence is |
| Answer» Coefficient = ∴ Coefficient = 0.6 ∠180°. | |
| 18. |
Assuming that flip-flops are in reset condition initially, the count sequence observed at Q in the circuit shown is |
| Answer» | |
| 19. |
The Taylor series expansion of at = is given by |
| Answer» . | |
| 20. |
In a series LCR circuit the maximum inductor voltage is twice the maximum capacitor voltage however current lags by 30° and drop across the inductance is = 100 sin 377 V. Assuming the resistance being 20 Ω, Find the values of the capacitance and inductance. |
| Answer» vL max = 100 V = ωL Imax 2Imax = ωL X ωC Imax ω2LC = 2 ω2LC = 2 | |
| 21. |
In 8085 microprocessor based system running at 3 MHz clock frequency what should be the minimum pulse width of the INTR signal, so that it is recognized successfully? |
| Answer» T = x 106 = 0.333 μs 8085 checks INTR, one clock period before the last T-state of an instruction cycle. In 8085, CALL instruction requires 18 T-states. ∴ INTR pulse should be high at least for 17.5 T-states i.e. for 17.5 x 0.33 x 10-6 = 5.8 μs long. | |
| 22. |
The step error coefficient of a system with unity feedback is : |
| Answer» kp = s → 0 G(s)H(s). | |
| 23. |
= 100 cos (10 + 30°)R = 10 Ω X = 10 ΩX = - 4 ΩFind V |
| Answer» VC = XC X I = 7.07 X 4∠ -90° - 60° = 28.28∠ - 150°V VR = I X R = 7.07 ∠-60° x 10 = 70.7∠ - 60° Vs = 70.7∠30° + 70.7∠-60° + 28.28∠-150° = 82.44∠-29° V vs = 116.57 sin (10t - 29°) V. | |
| 24. |
4 point DFT for () = {2, - 1, 2, 3} is |
| Answer» 1 point DFT X(k) = [W][x(n)]1 | |
| 25. |
Determine the voltage V in the circuit below: |
| Answer» = 2.3 mA ≈ IC VCB = CCC - ICRC = 12 - 2.3 x 2 = 7.4 V. | |
| 26. |
The Z-transform of a signal is given by its final value is __________ . |
| Answer» Final value Final value Final value . | |
| 27. |
The system shown in figure remains stable when : |
| Answer» Pi = 1 x k x s-1 x 1 ⇒ , L2 = k x s-1 System will be stable when k - 3 > 0 or k > 3. | |
| 28. |
The mechanical system shown below has its pole(s) at: |
| Answer» Kx(s) - Ky(s) = Dsy(s) Kx(s) = Dsy(s) + Ky(s) | |
| 29. |
The electric field vector of a wave in free space (ε, μ) isIts magnetic field vector will be given by |
| Answer» Now ∴ (use B = μ0 H) . | |
| 30. |
A uniform plane wave is described by the equation H = A/m. If the velocity of the wave is 2 x 10 m/s and ε = 1.8, then. The frequency of the wave is |
| Answer» r = 0.1p . | |
| 31. |
Find I for circuit shown below |
| Answer» Mesh Analysis Apply KVL at loop 2 125i2 - 100i3 = 0 ...(i) Apply KVL at loop 3 120i3 - 100i2 - 20i1 = 0 i1 = 5A ∴ 120i3 - 100i2 - 100 = 0 ∴ 120i3 - 100i2 = 100 ...(ii) From (i) 125i2 - 100i3 = 0 ...(iii) Put equation (iii) in eq. (ii) 120i 3 - 100i2 = 100 120 x - 100i2 = 100 150i2 - 100i2 = 100 ∴ 50i2 = 100 ∴ i2 = 2A. | |
| 32. |
A -type silicon sample contains a donor concentration of N = 2 x 10 cm. The minority carrier hole lifetime is = 5 μs. The thermal equilibrium generation rate of hole is: |
| Answer» Then thermal generation rate = 2.25 x 109 cm3 S-1 . | |
| 33. |
The reduced form of the functionX(E, A, B, C, D) = ∑(0, 1, 2, 3, 4, 7, 8, 9, 10, 12, 15, 16, 17, 18, 19, 20, 23, 24, 25, 26, 28, 31) is |
| Answer» X =(A + B + D)(A + B + D) (A + B + C + D) =(D + A D + B D + AB + A D + A B + B D) (A + B + C + D) =(D + AB + A B)(A + B + C + D) . | |
| 34. |
Consider the probability density = where is a random variable whose allowable values range from = - ∞ to = + ∞. The Cdf (Cumulative distribution function) for ≥ 0 is : |
| Answer» . | |
| 35. |
The electric field of uniform plane wave is given by = 20 sin (2 x 10- ) + 20 cos (2 x 10 - ) . The corresponding magnetic field is |
| Answer» ∴ H = Hx + Hy . | |
| 36. |
Consider two random processes and have zero mean, and they are individually stationary. The random process is = + . Now when stationary processes are uncorrelated then power spectral density of is given by |
| Answer» The autocorrelation function of z(t) is given by Rz(t, u) = E[Z(t)Z(u)] = E[(x(t) + y(t)) (x(u) + y(u))] = E[x(t) x (u)] + E[x(t) y(u)] + E[y(t) x(u)] + E[y(t) y(u)] = Rx(E, u) + Rxy(t, u) + Ryx(t, u) + Ry(t, u) Defining t = t - u, we may therefore write Rz(t) = Rx(t) + Rxy(t) + Ryx(t) + Ry(t). When the random process x(t) and y(t) are also jointly stationary. Accordingly, taking the fourier transform of both sides of equation we get Sz(f = Sx(f) + Sxy(f) + Syx(f) + Sy(f) We thus see that the cross spectral densities Sxy(f) and Syx(f) represent the spectral components that must be added to the individual power spectral densities of a pair of correlated random processes in order to obtain the power spectral density of their sum. When the stationary process x(t) and y(t) are uncorrelated the cross-sectional densities Sxy(f) and Syz(f) are zero ∴ Sz(f) = Sx(f) + Sy(f). | |
| 37. |
What is the frequency of pulse at the points , , in the circuit? |
| Answer» Ring counter is N : 1 divider. Hence ⇒ 1 MHz Johnson counter is 2N : 1 divider ⇒ Ripple counter 2N : 1 ⇒ = 7812.5 ∼ 7.8 kHz Mod 10 = 4 FF ⇒ 24 = 16. | |
| 38. |
A lossless transmission line with air dielectric is 6 m long. what is the phase constant? |
| Answer» . | |
| 39. |
The impulse response () of a linear invariant continuous time system is given by h() = exp (- 2) (), where () denotes the unit step function. The frequency response H(ω) of this system in terms of angular frequency ω is given by H(ω) |
| Answer» H(ω) = e-2t e-jωt | |
| 40. |
A surface charge density of 8 is present on a plane = . A line charge density of 30 C/ is present on line = 1, = 2 Find V for points A(3, 4, 0) and B(4, 0, 1) |
| Answer» Potential due to surface charge ∴ ∴ = 144pv = 452.16v Potential due to line charge at x = 1 and y = 2 | |
| 41. |
An air-filled rectangular waveguide has dimensions 8 x 10. The wavelength of waveguide at frequency 3 GH |
| Answer» λc = 2a = 2(10) = 20 cm = 1.5 GHz λg = 23.09 cm. | |
| 42. |
NMOS devices have __________ switching speeds and __________ on-state resistance; as compared with PMOS devices. |
| Answer» In NMOS devices, we have mobility of electrons than holes in PMOS; consequently higher conductivity and lower on-state resistance. | |
| 43. |
An antenna array comprises of two dipoles that are separated by wavelength. The dipoles are fed by currents of the same magnitude and 90° in phase. The array factor is: |
| Answer» Array factor φ = 90°. | |
| 44. |
In the signal flow graph of figure below, the gain C/R will be : |
| Answer» Forward path gain P1 = 2 x 3 x 4 ⇒ 24, P2 = 5, D1 = 1 D2 = - 3, L1 = - 2, L2 = - 3, L3 = - 4 Two non touching loop = L1 x L3 = - 2 x - 4 = 8 But if we take loop L4 into consideration then = 5 x -1 x - 1 x - 1 = -5 . | |
| 45. |
P(X) = M exp(- 2 ||) + N exp(- 3 ||) is the probability density function for the real random variable X, over the entire x axis. M and N are both positive real numbers. The equation relating M and N is |
| Answer» Using property of probability density of Pxdx = 1 [M exp(- 2 |x|) + N exp(- 3|x|)]dx 1 ⇒ . | |
| 46. |
The electric field component of a time harmonic plane EM wave travelling in a non magnetic lossless dielectric medium has an amplitude of 1 V/m. If the relative permittivity of the medium is 4, the magnitude of the time-average power density vector (in W/m) is |
| Answer» | |
| 47. |
The open loop transfer function of a unity feedback control system is given as The phase cross over frequency and the gain margin are respectively. |
| Answer» At phase cross over frequency -90° - tan- 1 ωT1 - tan- 1 ωcT2 = - p = 90° GM = 1/a where a = | G(jω)|ω=ωc . | |
| 48. |
A unity negative feedback closed loop system has a plant with the transfer function and a controller G(S) in the feed forward path. For a unit set input, the transfer function of the controller that gives minimum steady state error is |
| Answer» so, Gc(s)|s → 0 should be maximum for low error = ∞ Gc(s)|s → 0. | |
| 49. |
If X = 1 in the logic equation [X + Z { + ( + X )}] { + (X + Y)} = 1, then |
| Answer» [1 + z{y + z + y}][0 + z] = 1, z = 1, z = 0. | |
| 50. |
(22) + (101) - (20) = () + (4) where > 4. The value of is |
| Answer» (22)4 + (10)10 - (10)10 = (22)4 Since x > 4, i.e. all the number systems with base greater than 4. All these will contain symbol '4' which will have same value in all bases. Converting 4 into base '4' system (4)10 (10)4 Now (22)4 = (x)4 + (10)4 ∴ (x)4 = (22)4 - (10)4 = (12)4 ∴ x = 12. | |