# Electronics and Communication Engineering - Exam Questions Papers

21.
If the sequence converges, then the series converges absolutely is
Ratio test
Root test
Divergence test
Convergence test
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
1
zero
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

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
100000111
00000111
11111001
111111001
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 :
25
50
100
5000
Explanation:

.

25.
Consider the circuit shown below of 2 : 1 MUX is given by the function g = ac + bc

Then f is :
X ⊕ Y
XY + EXY
XE + XY
none of these