ae-at
$$left( {{1 over a}} ight)left( {1 - {e^{ - at}}} ight)$$
a(1 - e-at)
1 - e-at
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Answer is Wrong!
Signal processing
62. The unilateral Laplace transform of f(t) is $${1 \over {{s^2} + s + 1}}.$$ Which one of the following is the unilateral Laplace transform of g(t) = t.f(t)?
$${{ - s} over {{{left( {{s^2} + s + 1} ight)}^2}}}$$
$${{ - left( {2s + 1} ight)} over {{{left( {{s^2} + s + 1} ight)}^2}}}$$
$${s over {{{left( {{s^2} + s + 1} ight)}^2}}}$$
$${{2s + 1} over {{{left( {{s^2} + s + 1} ight)}^2}}}$$
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Answer is Wrong!
63. A 1 kHz sinusoidal signal is ideally sampled at 1500 samples/sec and the sampled signal is passed through an ideal low-pass filter with cutoff frequency 800 Hz. The output signal has the frequency
Zero Hz
0.75 kHz
0.5 kHz
0.25 kHz
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Answer is Wrong!
64. Flat top sampling of low pass signals
Gives rise to aperture effect
Implies oversampling
Leads to aliasing
Introduces delay distortion
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Answer is Wrong!
65. The Fourier series of an odd periodic function, contains only
Odd harmonics
Even harmonics
Cosine terms
Sine terms
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Answer is Wrong!
Detailed SolutionThe Fourier series of an odd periodic function, contains only
66. Consider the differential equation $${{dx} \over {dt}} = 10 – 0.2x$$ with initial conduction x(0) = 1. The response x(t) for t > 0 is
2 - e-0.2t
2 - e-0.2t
50 - 49e-0.2t
50 - 49e0.2t
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Answer is Wrong!
67. For a periodic signal $$v\left( t \right) = 30\sin 100t + 10\cos 300t + 6\sin \left( {500t + {\pi \over 4}} \right),$$ the fundamental frequency in rad/s is
100
300
500
1500
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Answer is Wrong!
68. Let y[n] denote the convolution of h[n] and g[n], where h[n] = $${\left( {\frac{1}{2}} \right)^n}$$ u[n] and g[n] is a causal sequence. If y[0] = 1 and y[1] = $$\frac{1}{2},$$ then g[1] equals
0
$${1 over 2}$$
1
$${3 over 2}$$
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Answer is Wrong!
69. The impulse response h[n] of a linear time-invariant system is given by h[n] = u[n + 3] + u[n – 2] – 2u[n – 7], where u[n] is the unit step sequence. The above system is
Stable but not causal
Stable and causal
Causal but unstable
Unstable and not causal
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Answer is Wrong!
70. A band-limited signal with a maximum frequency of 5 kHz is to be sampled. According to the sampling theorem, the sampling frequency which is not valid is
5 kHz
12 kHz
15 kHz
20 kHz
Answer is Right!
Answer is Wrong!