Electronics and Communication Engineering - Exam Questions Papers

Exercise :: Exam Questions Papers - Exam Paper 9

If X = 1 in the logic equation [X + Z { Y + (Z + X Y)}] { X + Z (X + Y)} = 1, then

A.	Y = Z
B.	Y = Z
C.	Z = 1
D.	Z = 0

Answer: Option D

Explanation:

[1 + z{y + z + y}][0 + z] = 1, z = 1, z = 0.

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(22)₄ + (101)₃ - (20)₅ = (x)₄ + (4)_x+1 where x > 4. The value of x is

A.	6
B.	4
C.	12
D.	8

Answer: Option C

Explanation:

(22)₄ + (10)₁₀ - (10)₁₀ = (22)₄

Since x > 4, i.e. all the number systems with base greater than 4.

All these will contain symbol '4' which will have same value in all bases.

Converting 4 into base '4'

system (4)₁₀ (10)₄

Now (22)₄ = (x)₄ + (10)₄

∴ (x)₄ = (22)₄ - (10)₄ = (12)₄

∴ x = 12.

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Consider a system with the transfer function . Its damping ratio will be 0.5 when the value of k is :

A.	2/6
B.	3
C.	1/6
D.	6

Answer: Option C

Explanation:

ξ = 0.5,

We take second term only

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For the system with given characteristic equation
s⁵ + 4s⁴ + 8s³ + 8s² + 7s + 4 = 0
The number of roots on left hand side, right hand side and imaginary axis are respectively.

A.	3, 2, 0
B.	4, 0, 1
C.	3, 0, 2
D.	4, 1, 0

Answer: Option D

Explanation:

Apply Routh Hurwitz criteria.

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A series RLC circuit has a resonance frequency of 1 kHz and a quality factor Q = 100. If each of R, L and C is doubled from its original value, the new Q of the circuit is