Electronics and Communication Engineering - Exam Questions Papers

21. 

If the sequence converges, then the series converges absolutely is

A. Ratio test
B. Root test
C. Divergence test
D. Convergence test

Answer: Option B

Explanation:

This is the Root test. Since the signal magnitude is raised to the power of 1/n.


22. 

Open loop transfer function of a system is

The phase cross over frequency ωc is

A.
B. 1
C. zero
D.

Answer: Option B

Explanation:

GH = - tan- 1 ω - tan- 1 2ω - tan- 1

= - p

tan- 1 ω + tan- 1 2ω = p - tan- 1

tan- l = p - tan- 1

= - 3ω

ω = 1 rad/sec.


23. 

The two numbers represent in signed 2's complement form are P = 11101101 and Q = 111001110. If Q subtracted from P, the value obtained in signed 2's complement form is

A. 100000111
B. 00000111
C. 11111001
D. 111111001

Answer: Option C

Explanation:

P = 11101101 = - 25

Q = 11100110 = - 18

Thus P - Q = - 25 - (- 18) = - 7

Thus '- 7's two complement representation is 11111001.


24. 

The transfer function of an RLC circuit is given by quality factor (Q-factor) of this circuit is :

A. 25
B. 50
C. 100
D. 5000

Answer: Option B

Explanation:

.


25. 

Consider the circuit shown below of 2 : 1 MUX is given by the function g = ac + bc

Then f is :

A. X ⊕ Y
B. XY + EXY
C. XE + XY
D. none of these

Answer: Option B

Explanation:

Since g = ac + bc

i.e. when c = 0, g = b and c = 1, g = a

Now we evaluate

f = (E)(X) + (0)(X) = EX

f = (X)(Y) + (EX)(Y) = XY + EXY.