Electronics and Communication Engineering - Exam Questions Papers

41. 

The Z-inverse of the given Z-transform is __________

A. unit step
B. unit ramp
C. unit impulse
D. unit parabola

Answer: Option C

Explanation:

value of

x(n) = d(n) impulse response.


42. 

Find the Fourier transform of the half cosine pulse as shown below :

A. 0.5 {sin c [0.25(f - 1)] + sin c [2.5(f + 1)]}
B. 0.5 {sin c [0.5(f - 1)] + sin c [0.5(f + 1)]}
C. 0.25 {sin c [0.25(f - 1)] + sin c [0.25 (f - 1)]}
D. 0.25 {sin c [0.5(f - 1)] + sin c [0.5(f - 1)]}

Answer: Option B

Explanation:

The given signal can be expressed as multiplication of x1(t) and x2(t) as shown below.

where A = 2, T/2 = 0.25 => T = 0.5

x(t) = x1(t) x x2(t)

=> X(f) = X1(f) * X2(f)

Now X1(f) = [δ(f - f0) + δ(f + f0)]

= [sin c [T(f - f0)] + sin c[T(f + f0)]]

Now, A = 2, T = 0.5 and f0 = = 1

=> X(f) = 0.5[sin c (0.5(f - 1)) + sin c (0.5(f + 1))].


43. 

The q-v relation of a capacitor is v = 1 + q + qx. Find the amount of energy required to charge this capacitor from q(t0) = 0 to q(t) = 5 C.

A.
B.
C.
D.

Answer: Option C

Explanation:


44. 

V-I relationship of a network N is given by, V = 8 - 4I.

The equivalent circuit to the network N is shown below
The values of IN and RN are

A. 0, 2
B. 0, 4
C. 2, 4
D. None of these

Answer: Option C

Explanation:

Given equivalent circuit is Norton's equivalent circuit

V = 8 - 4I

Put V = 0I = IN = 2 A

Put I = 0 V = VTH = 8 V

.


45. 

If the open-loop transfer function is a ratio of a numerator polynomial of degree 'm' and a denominator polynomial of degree 'n', then the integer (n - m) represents the number of:

A. breakaway points
B. unstable poles
C. separate root loci
D. asymptotes

Answer: Option D

Explanation:

Asymptotes.