# Signals And Systems I

20 Questions | Total Attempts: 173  Settings  .

• 1.
A half – wave rectified sinusoidal waveform has a peak voltage of 10 V. Its average value and the peak value of the fundamental component are respectively given by:
• A.

6.366,7.07

• B.

3.183,7.07

• C.

3.183,5

• D.

6.366,5

• 2.
Which of the following signals is not periodic?
• A.

S(t) = cos 2t + cos 3t + cos 5t

• B.

S(t) = exp(j8πt)

• C.

Exp(-7t)sin 10πt

• D.

S(t) = cos 2t cos 4t

• 3.
The Laplace Transforms of the functions t u(t) and u(t) sin(t) are respectively:
• A.

1/s^2 , s/( s^2+1)

• B.

1/s , 1/( s^2+1)

• C.

1/s^2 , 1/( s^2+1)

• D.

S , s/( s^2+1)`

• 4.
A system with an input x(t) and output y(t) is described by the relation: y(t)=t x(t).This system is
• A.

linear and time-invariant (b) linear and time varying (c) non-linear and time-invariant

• B.

linear and time varying

• C.

Non-linear and time-varying

• D.

non-linear and time-invariant

• 5.
If a signal f(t) has energy E, the energy of the signal f(2t) is equal to
• A.

E

• B.

E/2

• C.

2E

• D.

4E

• 6.
Let x(t) be the input to a linear, time-invariant system. The required output is 4x(t-2). The transfer function of the system should be:
• A.

4exp(j4*pi*f)

• B.

2exp(-j8*pi*f)

• C.

4exp(-j4*pi*f)

• D.

2exp(j8*pi*f)

• 7.
The impulse response h[n] of a linear time-invariant system is given by h[n]=u[n+3] + u[n+2] – 2 u[n-7] where u[n] is the unit step response sequence. The above system is:
• A.

(a) Stable but not causal

• B.

(b) Stable and causal

• C.

(c) Causal but unstable

• D.

(d) Unstable and not causal

• 8.
If the Laplace transform of a signal y(t) is Y(s)= 1/(s(s-1)), then its final value is
• A.

-1

• B.

0

• C.

1

• D.

Unbounded

• 9.
The input and output of a continuous time system are respectively denoted by x(t) and y(t). Which of the following descriptions is corresponds to a causal system?
• A.

Y(t) = x(t-2) + x(t+4)

• B.

(b) y(t) = (t-4) x(t+1)

• C.

(c) y(t) = (t+4) x(t-1)

• D.

(d) y(t) = (t+5) x(t+5)

• 10.
The output of this system, to the sinusoidal input x(t)=2cos(2t) for all the time t, is
• A.

(a) 0

• B.

(b) 2^(0.25) cos(2t-0.125*pi)

• C.

(c) 2^(0.5) cos(2t-0.125*pi)

• D.

(d) 2^(0.5) cos(2t-0.25*pi)

• 11.
The trigonometric Fourier series of an even function does not even have the
• A.

Dc term

• B.

(b) Cosine terms

• C.

(c) Sine terms

• D.

(d) Odd terms `

• 12.
A system with input x[n] and output y[n] is given as y[n]= (sin(5/6)*pi*n) x(n) .The system is (sin(5/6)*pi*n) x(n) .
• A.

(a) linear, stable

• B.

(b) non-linear, stable

• C.

(c) linear, stable

• D.

(d) linear, unstable

• 13.
A 1kHz sinusoidal signal is ideally sampled at 1500 samples/sec and the sampled signal is passed through an ideal low pass filter with cut-off frequency 800 Hz. The output signal has the frequency
• A.

Zero Hz

• B.

0.75 Hz

• C.

0.5 Hz

• D.

0.25 Hz

• 14.
The covolution of an even and odd function yields
• A.

Always an even function

• B.

Always an odd function

• C.

Both even and odd funtion

• D.

Depends on the originals functions

• 15.
The colvolution of two similar width rectangular functions yields
• A.

Ramp

• B.

Step

• C.

Trapezoid

• D.

Triangle

• 16.
System linearity refers to which property?
• A.

• B.

Scaling

• C.

• D.

Homogeneity

• 17.
To  draw a signal which is both time scaled and time shifted,what is the order of operation?
• A.

First scaling then shifting

• B.

First shifting then scaling

• C.

Order is immaterial

• D.

None

• 18.
In what range should Re(s) remain so that the L.T. of the function e(a+2)t+5  exists?
• A.

Re(s) > a+2

• B.

. Re(s) > a+7

• C.

Re(s)

• D.

Re(s) > a+5

• 19.
Convolution of a step function with itself produces
• A.

Step

• B.

Ramp

• C.

Parabolic

• D.

Impulse

• 20.
On expanding a time limited signal,its
• A.

Energy remains unchanged

• B.

Energy decreases

• C.

Energy increases

• D.

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