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Electronics and Communication Engineering - Signals and Systems

Exercise : Signals and Systems - Section 4
31.
If then system is
casual
uncasual
casual at z = 0.4, 2
uncasual at z = 0.4, z = 2
Answer: Option
Explanation:

ROC will be |z| > 0.4 and |z| > 2

Hence ROC ⇒ |z| > 0.4, which is exterior of circle of radius 0.4

Hence causal if ROC is |z| > 0.4 then non-causal.

32.
A pulse function having magnitude E and duration from t = 0 to t = a can be represented as
sum of two pulse functions
difference of two pulse functions
difference of two step functions each of magnitude E and one originating at t = 0 and the other at t = a
none of the above
Answer: Option
Explanation:

v(t) = Eu(t) - Eu(t - a).

33.
If , f(t) =
10 te-2t
10 t2e-2t
10 e-2t
5 t2e-2t
Answer: Option
Explanation:

.

34.
If I(s) = , initial value of i(t) is
0
5 A
10 A
- 5A
Answer: Option
Explanation:

.

35.
The DTFT of x(n) = δ(n) will be
1
0
∞
not defined
Answer: Option
Explanation:

DTFT of x(n) ⇒ x(ω) .

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