Q.1

The analog signal given below is sampled bysamples per second for m(t) = 3 sinpt + 2 sinpt then folding frequency is

  • 500 Hz
  • 700 Hz
  • 300 Hz
  • 1400 Hz
Q.2

If £[f(t)] = F(s), then £[f(t - T)] =

  • est F(s)
    13-168-3.png
    13-168-4.png
  • e-st F(s)
    13-168-3.png
    13-168-4.png
Q.3

If v(t) is a time varying voltage, is

  • initial current
  • initial voltage
  • initial charge
  • initial flux leakages
Q.4

If is the Laplace transform of f(t) then f(0+) is

  • 0
    23-387-2.png
  • 27
  • ∞
Q.5

Z transform is a non-linear operation.

  • True
  • False
Q.6

In Laplace transform, multiplication by e-at in time domain becomes

  • translation by a in s domain
  • translation by (-a) in s domain
  • multiplication by e-as in s domain
  • none of the above
Q.7

If I (s) , the final value of i(t) is

  • 0.05 A
  • 5A
  • 12.5 A
  • 1250 A
Q.8

The period of the function cos is

  • 8s
    12-158-4.png
  • 4s
    12-158-4.png
Q.9

If is the Laplace transform of f(t) then f(0+) is

  • 0
    23-387-2.png
  • 27
  • ∞
Q.10

As per time displacement theorem in Laplace transformation, displacement in the time domain by T becomes

  • division by s in the s domain
  • division by e-sT in the s domain
  • multiplication by s in the s domain
  • multiplication by e-sT in the s domain
Q.11

If I (s) , the final value of i(t) is

  • 5A
  • 12.5 A
  • 0.05 A
  • 1250 A
Q.12

If I (s) , the final value of i(t) is

  • 5A
  • 12.5 A
  • 0.05 A
  • 1250 A
Q.13

If I (s) , the final value of i(t) is

  • 5A
  • 12.5 A
  • 0.05 A
  • 1250 A
Q.14

Z transform is a non-linear operation.

  • True
  • False
Q.15

Which one is a linear system?

  • y[n] = x[n] x x[n - 1]
  • y[n] = x[n] + x[n - 10]
  • y[n] = x2[n]
  • (a) and (c)
Q.16

A voltage wave v =+sin ωt + 7.5 sin 3 ω(t) is applied to a series combination of two elements. The current is i = 5 sin (ωt + 20°) + 1.5 sin (3ωt + 10°). The elements are

  • R and C
  • R and L
  • L and C
  • both inductances
Q.17

If f(t) is in volts, then F(jω) is in

  • volts
  • volt seconds
  • volts/sec
  • volt-sec2
Q.18

If F(t) = δ(t - a), F(s)=

  • 0
  • 1
  • e-as
  • eas
Q.19

X and Y are two random variable and Z = X + Y. Let σx2, σy2 and σz2 be variance of X, Y and Z. Then

  • σz2 = σx2 + σy2
  • σz2 ≤ σx2 + σy2
  • σz2 < σx2 + σy2
  • σz2 > σx2 + σy2
Q.20

If f=0

  • XL = 0 and XC = 0
  • XL = ∞, XC = ∞
  • XL = 0 and XC = ∞
  • XL = ∞ and XC = 0
Q.21

Fourier transform of an external exponential ejW0t

  • δ(f - f0)
  • 1
  • δ(f + f0)
  • ∞
Q.22

If X(z) = (1 - az-1), and |a| < |z|, the initial value x0 is

  • 1
  • 0
  • 2
  • ∞
Q.23

Which one most appropriate dynamic system?

  • y(n) + y(n - 1) + y(n + 1)
  • y(n) + y(n - 1)
  • y(n) = x(n)
  • y(n) + y(n - 1) + y(n + 3) = 0
Q.24

A voltage V(t) which is a Gaussian ergodic random process with a mean of zero and a variance of 4 volt2 is measured by a true rms meter. The reading will be

  • 0
  • 4
  • 2
  • 16
Q.25

L [f(t - a)] = F(jω) e-jωa

  • True
  • False
Q.26

When a complex voltage wave is applied to a capacitor the resulting current wave is more distorted than the voltage wave.

  • True
  • False
Q.27

Fourier transform is defined for

  • periodic
  • non-periodic
  • finite duration
  • all
Q.28

The property is not valid for basic singularity function is

  • it is even signal
  • convolution of any arbitary function x(t) and an impulse is the original function itself
  • the sum of two impulses at same location is the impulse with the strength equal to the summation of individual strengths.
  • none of these.
Q.29

Which one most appropriate dynamic system?

  • y(n) + y(n - 1) + y(n + 1)
  • y(n) + y(n - 1)
  • y(n) = x(n)
  • y(n) + y(n - 1) + y(n + 3) = 0
Q.30

If i =+cos 500t - 3.5 sint, then in amplitude phasse form i =

  • 10 + 12.5 sin (500 t + 106.20°)
  • 5 + 12.5 sin (500 t + 106.20°)
  • 10 + 11 sin (500 t + 106.20°)
  • 10 + 12.5 sin (500 t + 10°)
Q.31

The integral of a unit impulse is

  • a unit step function
  • a ramp function of slope 1
  • a pulse function of magnitude 1
  • none of the above
Q.32

An energy signal has G(f) =Its energy density spectrum is

  • 10
  • 100
  • 50
  • 20
Q.33

The integral of k δ(t) is

  • a step function of magnitude k
  • a step function 'of magnitude 1/k
  • a ramp of slope k
  • a ramp of slope 1/k
Q.34

The units of the spectrum obtained be Fourier transforming the covariance function of a stationery Stochastic Process is

  • Power per Hz
  • energy per Hz
  • Power per sec
  • Energy per second
Q.35

If xk = ak and k < 0
X(z) = - (1 - az-1)-1 with |z| < |a|

  • True
  • False
Q.36

Magnitude Plot of a Composite signal x(t) = e2jt + e3jt is

  • half wave rectified sinusoidal
  • full wave rectified sinusoidal
  • exponentially increasing sinusoidal
  • exponentially decreasing sinusoidal
Q.37

Assertion (A): The conditions under which it is possible to write Fourier series of a periodic function are called Drichlet conditions.

Reason (R): If f(t) = - f(- t), it is refereed to as odd symmetry.

  • Both A and R are correct and R is correct explanation of A
  • Both A and R are correct but R is not correct explanation of A
  • A is true, R is false
  • A is false, R is true
Q.38

The ROC of sequence x[n] = (0.8)n ∪[n] + (0.4)n ∪[n]

  • |z| > 0.8
  • |z| > 0.4
  • 0.4 < |z| < 0.8
  • |z| < 0.8
Q.39

The real part of complex frequency s corresponds to oscillations.

  • True
  • False
Q.40

The z-transform of sequence x[n] = δ(n) is

  • 1
  • ∞
  • 0
  • z
Q.41

For Binomial Distribution

  • mean = np, Variance = npq
    17-267-3.png
    17-267-4.png
  • mean = npq, Variance = np
    17-267-3.png
    17-267-4.png
Q.42

Two rectangular waveforms of duration t1 and t2 seconds are convolved. What is the shape of the resulting waveform?

  • Triangular
  • Rectangular
  • Trapezoidal
  • Semi-circular
Q.43

The function A est where s = s + jω represents

  • A phasor whose magnitude changes with time
  • A phasor whose frequency is ω
  • A phasor rotating in counterclockwise direction at angular frequency ω and whose magnitude increases with t
  • A phasor rotating in clockwise direction at angular frequency ω and whose magnitude increases with t
Q.44

An ac circuit has an impedance of (3 + johm for fundamental. The impedance for fifth harmonic is

  • (15 + j 30) Ω
  • (15 + j 6) Ω
  • (3 + j 30) Ω
  • (3 + j 1.2) Ω
Q.45

The integral of unit step function is a ramp of slope unity.

  • True
  • False
Q.46

Which one of the systems described by the following I/P - O/P relations is time invariant

  • y(n) = n x(n)
  • y(n) = x(n) - x(n - 1)
  • y(n) = x(- n)
  • y(n) = x(n) cos 2pf0n
Q.47

Two rectangular waveforms of duration t1 and t2 seconds are convolved. What is the shape of the resulting waveform?

  • Triangular
  • Rectangular
  • Trapezoidal
  • Semi-circular
Q.48

FIR digital filter having __________ stability than FIR filter.

  • good stability
  • poor stability
  • stability not guarnteed
  • poor stability
Q.49

Fourier transform of non periodic DT signal is

  • aperiodic
  • Periodic
  • both a and b
  • None of these
Q.50

The derivative of unit step function is

  • unit impulse
  • ramp with slope 1
  • impulse
  • either (a) or (b)
0 h : 0 m : 1 s