Online Electronics and Communication Engineering Test - Previous Exam Papers Test 5



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Instruction:

  • This is a FREE online test. DO NOT pay money to anyone to attend this test.
  • Total number of questions : 20.
  • Time alloted : 30 minutes.
  • Each question carry 1 mark, no negative marks.
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  • All the best :-).


1.

What are the values of Emax and Emin displayed on the oscilloscope, when a 1 kV P-P carries is modulated to 50%?

A.
2 kV, 0.5 kV
B.
1 kV, 0.5 kV
C.
0.75 kV, 0.25 kV
D.
0.5 kV, 1.5 kV

Your Answer: Option (Not Answered)

Correct Answer: Option C

Explanation:

Emax - Emin = 0.5 x 1 kV = 0.5 kV

2Emax = 1.5 kVi, Emax = 0.75 kV

Emin = 0.25 kV.

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2.

The equation sin (z) = 10 has

A.
no real or complex solution
B.
exactly two distinct complex solutions
C.
a unique solution
D.
an infinite number of complex solutions

Your Answer: Option (Not Answered)

Correct Answer: Option A

Explanation:

Since value lies between - 1 and + 1. Therefore no real or complex solution exists.

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3.

The logic function f(A B, C) = Σm(0, 2, 4, 5, 6) represented by

A.
i
B.
i, ii
C.
i, iii
D.
i, ii, iii

Your Answer: Option (Not Answered)

Correct Answer: Option B

Explanation:

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4.

In the given figure
.
The damping coefficient for the given circuit is __________ .

A.
1/2
B.
1/4
C.
2
D.
1

Your Answer: Option (Not Answered)

Correct Answer: Option A

Explanation:

Damping coefficient is given by,

Substituting R = 1 Ω, L = 1 H

.

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5.

Find current i.

A.
4/5 A
B.
5/4 A
C.
1.23 A
D.
1.32 A

Your Answer: Option (Not Answered)

Correct Answer: Option A

Explanation:

The given circuit can be compared with Wheatstone's Bridge

Req = (10 + 10 + 10) || (10 + 10 + 10) = 30 || 30 = 15 Ω

.

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6.

The Vs is given by

A.
8 V
B.
13 V
C.
1 V
D.
4 V

Your Answer: Option (Not Answered)

Correct Answer: Option B

Explanation:

Using Nodal analysis

...(i)

...(ii)

V2 = 2Vx

V2 = 2V ...(iii)

...(iv)

Put V2 = 2V

Put in equation (iii), Vs = 3V1 - V2

Vs = 3 x (+5V) - 2V

Vs = 15V - 2V = 13V.

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7.

For the 8085 assembly language program given below, the content of the accumulator after the execution of the program is

A.
00H
B.
45H
C.
67H
D.
E7H

Your Answer: Option (Not Answered)

Correct Answer: Option C

Explanation:

A → 0100 0101

B → 0100 0101

Carry flag → 0

RAR will A → 0010 0010

XRA B 0110 0111

67.

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8.

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)]}

Your Answer: Option (Not Answered)

Correct 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))].

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9.

In the signal flow graph of figure, y/x equals.

A.
3
B.
5/2
C.
2
D.
None of the above

Your Answer: Option (Not Answered)

Correct Answer: Option C

Explanation:

P1 = 5 x 2 x 1 = 10

L1 = - 4

.

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10.

A system with transfer function has an output for the input signal . Then, the system parameter 'p' is

A.
3
B.
C.
1
D.

Your Answer: Option (Not Answered)

Correct Answer: Option B

Explanation:

|y(t)| = |M(ω)||x(t)|.

ω2 + p2 = ω2p2, 4 + p2 = 4p2

3p2 = 4, .

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11.

The Taylor series expansion of at x = p is given by

A.
B.
C.
D.

Your Answer: Option (Not Answered)

Correct Answer: Option D

Explanation:

.

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12.

Consider the voltage transfer characteristic of a standard CMOS inverter

where region A corresponds to

A.
NMOS and PMOS triode
B.
Both are saturation
C.
NMOS saturated PMOS linear
D.
None of these

Your Answer: Option (Not Answered)

Correct Answer: Option C

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13.

Which one of the following is applicable to any network-linear or non-linear, active or passive, time-varying or invariant - as long as Kirchhoff laws are not violated?

A.
Tellegen's theorem
B.
Reciprocity theorem
C.
Maximum power transfer theorem
D.
Superposition theorem

Your Answer: Option (Not Answered)

Correct Answer: Option A

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14.

In a network with twelve circuit elements and five nodes, what is the minimum number of mesh equations?

A.
24
B.
12
C.
10
D.
8

Your Answer: Option (Not Answered)

Correct Answer: Option D

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15.

Assertion (A): The expression E = - ΔV, where E is the electric field and V is the potential is not valid for time varying fields.

Reason (R): The curl of a gradient is identically zero.

A.
Both A and R are individually true and R is the correct explanation of A
B.
Both A and R are individually true but R is not the correct explanation of A
C.
A is true but R is false
D.
A is false but R is true

Your Answer: Option (Not Answered)

Correct Answer: Option B

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16.

Which of the following are included in the architecture of a computer?

  1. Addressing modes, CPU
  2. Instruction set, data formats
  3. Secondary memory, operating system
Select the correct answer from the codes given below:

A.
1 and 2
B.
1 and 3
C.
2 and 3
D.
3 only

Your Answer: Option (Not Answered)

Correct Answer: Option A

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17.

Consider the following statements:
The klystron and travelling wave tube differ from each other,

  1. In TWT the microwave circuit is non- resonant.
  2. In klystron the microwave circuit is resonant.
  3. TWT uses attenuator.
  4. The wave is TWT is a non-propagating wave.
Which of the above statements are correct?

A.
1 and 2 only
B.
3 and 4 only
C.
1, 2 and 3
D.
2, 3 and 4

Your Answer: Option (Not Answered)

Correct Answer: Option C

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18.

Consider the function where F(s) is the Laplace transform of f(t). What is the steady-state value of f(t)?

A.
Zero
B.
One
C.
Two
D.
A value between - 1 and + 1

Your Answer: Option (Not Answered)

Correct Answer: Option D

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19.

A magnetic field in air is measured to be

What current distribution leads to this field?
[Hint: The algebra is trivial in cylindrical coordinates.]

A.
B.
C.
D.
0

Your Answer: Option (Not Answered)

Correct Answer: Option C

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20.

Which of the following photodetector does not provide gain?

A.
Phototransistor
B.
Photoconductor
C.
Avalanche photodiode
D.
p-i-n photodiode

Your Answer: Option (Not Answered)

Correct Answer: Option D

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