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Electronics and Communication Engineering - Signals and Systems

Exercise : Signals and Systems - Section 3
31.
A signal is sampled at Nyquist rate fs = 2f0. The function can be recovered from its samples only. If it is a
Periodic square wave of fundamental frequency f0
Triangular wave of fundamental frequency f0
Periodic sine wave of fundamental frequency f0
Unit impulse function
Answer: Option
Explanation:

Nyqist theorem is defined with respect to sinusoidal signal.

32.
A voltage wave is v = 50 sin ωt. Its average value calculated over full one cycle is
zero
35.36 V
31.85 V
none of the above
Answer: Option
Explanation:

Average of sinusoid over full cycle is zero.

33.
If f1 (t) and f2 (f) are two functions of time and a and b are constants, then
L [af1(t) + bf2(t)] = aF1(s) + bF2(s)
L [af1(t) + bf2(t)] = aF1(s) - bF2(s)
L [af1(t) + bf2(t)] =[aF1(s)]/[bF2(s]
None of the above
Answer: Option
Explanation:

£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.

34.
The z transform of x(n) = ∪(n)
Answer: Option
Explanation:

.

35.
Fourier transform of f(t) =
jω F(f)
2pf F(f)
F'(f)
None
Answer: Option
Explanation:

It is differentiational Property of F.T. .

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