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Electronics and Communication Engineering - Signals and Systems

Exercise : Signals and Systems - Section 3
26.

Assertion (A): The unit impulse function is also known as Dirac delta function.

Reason (R): If a voltage

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
Answer: Option
Explanation:

For an inductor, L the current is and integral of d(t - a) is u(t - a).

27.
DTFT (Discrete time Fourier transform) of x[n] = an∪[n] for -1 < a < + 1.
Answer: Option
Explanation:

.

28.
The z- transform of a systerm is If the ROC is |z| < 0.2, then the impluse response of the system is
(0.2)n ∪[n]
(0.2)n ∪[- n - 1]
-(0.2)n ∪[n]
-(0.2)n ∪[- n - 1]
Answer: Option
Explanation:

ROC is |z| < 0.2, which shows x(n) must be non-causal, therefore sequence must be left handed.

But given is z-transform of right handed sequence.

But if H(z) become then ROC become |z| < 0.2 and inverse z-transform of is - (0.2)n ∪(- n - 1).

29.
ROC of sequence x[n] = (3)n ∪[n] + (4)n ∪[- n - 1]
|z| > 4
3 < |z| < 4
|z| < 4
|z| > 3
Answer: Option
Explanation:

x[n] = (3)n ∪(n) + (4)n ∪(- n - 1)

30.
δ(t - b) is a pulse function.
True
False
Answer: Option
Explanation:

It is an impulse function occuring at t = b.

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