Electronics and Communication Engineering - Signals and Systems

1. 

If f=0

A. XL = 0 and XC = 0
B. XL = ∞, XC = ∞
C. XL = 0 and XC = ∞
D. XL = ∞ and XC = 0

Answer: Option C

Explanation:

.


2. 

An ac circuit has an impedance of (2 - j 9) Ω for third harmonic. The impedance for fundamental is

A. 6 - j 27 Ω
B.
C. 2 - j 27 Ω
D. 2 - j 3 Ω

Answer: Option C

Explanation:

.


3. 

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

A. |z| > 0.8
B. |z| > 0.4
C. 0.4 < |z| < 0.8
D. |z| < 0.8

Answer: Option A

Explanation:

ROC ⇒ 1 - 0.8 z-1 < 0 1 - 0.4 z-1

⇒ 1 > 0.8 z-1z > 0.4

or z > 0.8

By combining both condition

ROC because z > 0.4

If you consider z > 0.8 then ROC between the limit 0 to 0.4 excluded.


4. 

Pick the odd one

A. variance
B. standard deviation
C. expectation
D. chebyshev inequality

Answer: Option D

Explanation:

Because Variance, standard Deviation, Expectation are related to each other.


5. 

The sampling of a function f(l) = sin 2pf0t starts from a zero crossing. The signal can be detected if sampling time T is

A.
B.
C.
D.

Answer: Option C

Explanation:

Because fs ≤ 2f0, Ts.


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