InterviewSolution
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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.
| 51. |
The DTFT of () = δ() will be |
| Answer» DTFT of x(n) ⇒ x(ω) . | |
| 52. |
Fourier transform of - () is |
| Answer» It is duality property of differentiation. | |
| 53. |
A casual system having the transfer function is excited with 10 ∪(). The time at which the output reaches 99% of its steady-state value is |
| Answer» . | |
| 54. |
For exponential function the Laplace transform 1/( - ) |
| Answer» . | |
| 55. |
Consider the sequence [] = [- 4 - 5 1 + J2 4] |
| Answer» Conjugate ant-symmetric part | |
| 56. |
The trignometric Fourier series of an even function of time does not have |
| Answer» An even function cannot have sine terms because for an even function f( - x) = f(x). | |
| 57. |
A voltage wave is = 100 sin (ω). Its average value calculated over one half cycle is |
| Answer» . | |
| 58. |
In the given figure 15.5 show a discrete time system consisting of a unit delay system, a multiplier and a summer, such that () = ( - 1) + 0.5 (). This system |
| Answer» All the elements are linear. | |
| 59. |
An RLC series circuit has a variable inductance. The value of L for resonance conditions at fundamental frequency is 0.18 H. For resonance conditions at third harmonic frequency the value of inductance is |
| Answer» . | |
| 60. |
If function () has an initial value (0) at = 0, the Laplace transform of is |
| Answer» £f(t) = £-1F(s) = f(t) £[a f1(t) + bf2(t)] = aF1(s) + bF2(s) where £[f(t - T)] = e-sT F(s) £[e-at f(t)] = F(s + a) Initial value theorem Final value theroem Convolution Integral where t is dummy variable for t. | |
| 61. |
Z transformer of |
| Answer» Z transform possesses the property of linearity. | |
| 62. |
An ac wave with superimposed dc is symmetrical about - axis. |
| Answer» It is not symmetrical about x - axis. | |
| 63. |
State variables which describe a system are a unique set. |
| Answer» It is not a unique set. | |
| 64. |
Which one is a non-causal system? |
| Answer» Because in (a) if you put n = 1 then y(n) = x(2) which shows output depend upon future value. While in (b), (c) input converted to Past or Present and past. Note that n cannot be in fraction so for x(n/2) you will put n = 2, 4, ... etc. not 1, 3, 5 .... etc. | |
| 65. |
A linear system is characterized by H(ω) = B the system is physically |
| Answer» Exponential function cannot be linear. | |
| 66. |
A rectangular pulse is passed through an L.P.F. The response is a |
| Answer» Because LPF is an integrator circuit, if we integrate Rectangular Pulse it converted to triangular. | |
| 67. |
Consider transform of a signal as given belowthen the response will be |
| Answer» If we solve the expression, we get H(z) in which, we get multiple poles at the origin and no poles outside. Hence it is an FIR system. | |
| 68. |
The eigen values of matrix are |
| Answer» Eigen values of matrix A are roots of characteristic equation. [λ1- A] = 0 where λ is a scalar. Therefore (λ + 1)(λ - 1) = 0. The roots are - 1 and + 1. | |
| 69. |
A signal () = cos 10 + 3 cos 4 is instantaneously sampled. The maximum allowable value of sampling interval T in sec is |
| Answer» fs = 2 fm where fm is the highest frequency component. so . | |
| 70. |
The current in a circuit with 10 Ω resistance is = 3 + 4 sin (100 + 45°) + 4 sin (300 + 60°) A. The rms current and power dissipated are |
| Answer» . | |
| 71. |
Fourier transform pair are |
| Answer» This is property of autocorrelation. F[R1, 1 (t)] = s(f) where s(f) is Power spectral density. | |
| 72. |
The function () is shown in the given figure. Even and odd parts of a unit step function ∪ () are respectively, |
| Answer» | |
| 73. |
A voltage v = 5 + 50 sin ω/ + 5 sin 5 &omega is applied to a pure capacitor of capacitance 1 ωF. If /= 314 rad/sec, current is |
| Answer» . | |
| 74. |
The stationary process has |
| Answer» where f(x) is probability density function. | |
| 75. |
If () = 2 sin + cos 4 and () = sin 5 + 3 sin 13 then |
| Answer» . | |
| 76. |
An ac network has a power factor of 0.8 leading if the applied wave is of fundamental frequency. If the applied wave contains third and fifth harmonics, the overall power factor will be |
| Answer» As frequency increases, XC decreases and power factor improves. | |
| 77. |
If Laplace transform of () is F(), then £ ( - ) ( - )= 0 |
| Answer» £f(t) = £-1F(s) = f(t) £[a f1(t) + bf2(t)] = aF1(s) + bF2(s) where £[f(t - T)] = e-sT F(s) £[e-at f(t)] = F(s + a) Initial value theorem Final value theroem Convolution Integral where t is dummy variable for t. | |
| 78. |
The Laplace transform of impulse δ() is |
| Answer» £f(t) = £-1F(s) = f(t) £[a f1(t) + bf2(t)] = aF1(s) + bF2(s) where £[f(t - T)] = e-sT F(s) £[e-at f(t)] = F(s + a) Initial value theorem Final value theroem Convolution Integral where t is dummy variable for t. | |
| 79. |
If () is a time varying current, is |
| Answer» Intergal of current is charge. | |
| 80. |
The initial value theorem is |
| Answer» £f(t) = £-1F(s) = f(t) £[a f1(t) + bf2(t)] = aF1(s) + bF2(s) where £[f(t - T)] = e-sT F(s) £[e-at f(t)] = F(s + a) Initial value theorem Final value theroem Convolution Integral where t is dummy variable for t. | |
| 81. |
The exponential form of Fourier series is |
| Answer» Both a and b are exactly the same except the way of writing. | |
| 82. |
Principle of superposition is applicable to |
| Answer» Superposition is valid if response is linearly related to cause. | |
| 83. |
The range of value "" for which system will be stable. If impulse response of DT system is = ∪[] |
| Answer» Given n(n) = an ∪(n) ROC is |z| > a open the mod function when z > 0 ⇒ z > a z < 0 ⇒ - z > a or ⇒ z < - a For stability ROC must include unit circle, so |z| > a or - a < z < + a or -1 < a < + 1. | |
| 84. |
The signal is |
| Answer» To because Periodic such signal = rational number, where T1 and T2 is period of individual signal. | |
| 85. |
In the state equation = AX + B is a x matrix. |
| Answer» A is n x n matrix. | |
| 86. |
If the poles of H() are at |
| Answer» . | |
| 87. |
Energy density spectrum of [] = ∪[] for -1 < < + 1 is |
| Answer» | |
| 88. |
If () = - (- ) satisfies Drichlet conditions, then () can be expanded in Fourier series containing |
| Answer» Since f( - t) = - f(t) only sine terms will be present because sin (- x) = - sin x. | |
| 89. |
The joint probability function of two discrete random variable X and Y is given by = 0, 2, = 2, 3 then E() is |
| Answer» . | |
| 90. |
The joint probability function of two discrete random variable X and Y is given by = 0, 2, = 2, 3 variance σ will be[Hint: σ = E(X) - μ ⇒ E(X) - (E(X))] |
| Answer» . | |
| 91. |
A probability density function is given by () = K for -∞ < < ∞ , The value of K should be |
| Answer» K can be found by integrating and equating the area under the curve equal to 1. | |
| 92. |
The Laplace transform of () is |
| Answer» £f(t) = £-1F(s) = f(t) £[a f1(t) + bf2(t)] = aF1(s) + bF2(s) where £[f(t - T)] = e-sT F(s) £[e-at f(t)] = F(s + a) Initial value theorem Final value theroem Convolution Integral where t is dummy variable for t. | |
| 93. |
The function () in the given figure will have its Laplace transform as |
| Answer» The function is sum of three functions , i.e., a ramp of slpoe 1 originating at t = 0, a ramp of slpoe - 1 Originating at t = 1 and a negative unit step function originating at t = 2, i.e., f(t) = tu(t) - t u(t -1) = u(-2) . | |
| 94. |
The joint probability function of two discrete random variable X and Y is given by = 0, 2, = 2, 3 then E(X) = |
| Answer» . | |
| 95. |
Laplace transform of unit doublet is |
| Answer» Unit doublet is . | |
| 96. |
The integral of a unit step function is |
| Answer» . | |
| 97. |
Highest value of autocorrelation function 100 sin 50 is |
| Answer» Highest value of autocorrelation is at origin and that is called Energy. | |
| 98. |
A unit impulse voltage is applied to an inductance at = 0. The current at = 0 will be |
| Answer» . | |
| 99. |
A voltage wave containing 10% third harmonic is applied to a scries R-L circuit. The percentage third harmonic content in the current wave will be |
| Answer» . | |
| 100. |
The effective value of the waveform in the given figure is |
| Answer» . | |