Online Electronics and Communication Engineering Test - Electronics and Communication Engineering Test - Random

Instruction:

  • This is a FREE online test. Beware of scammers who ask for money to attend this test.
  • Total number of questions: 20.
  • Time allotted: 30 minutes.
  • Each question carries 1 mark; there are no negative marks.
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  • All the best!

Marks : 2/20


Total number of questions
20
Number of answered questions
0
Number of unanswered questions
20
Test Review : View answers and explanation for this test.

1.
If B = 4 + j3, (B)1/3 =
2 ∠30°
2 ∠36.87°
1.71 ∠12.3°
1.71 ∠30°
Your Answer: Option
(Not Answered)
Correct Answer: Option
Explanation:

4 + j3 = 5∠36.87°


2.
Kirchoff's laws are applicable to
steady state conditions only
transient conditions only
both steady state and transient condition
both steady state and transient condition but with some constraints
Your Answer: Option
(Not Answered)
Correct Answer: Option

3.
If wave of critical frequency 30 MHz is departing at an angle of 60°, then the MUF is given to be
10 MHz
15 MHz
30 MHz
60 MHz
Your Answer: Option
(Not Answered)
Correct Answer: Option
Explanation:

MUF = fc sec θ


4.
The coil of a moving iron instrument has a resistance of 500 Ω and an inductance of 1 H. It reads 250 V when a 250 V dc is applied. If series resistance is 2000 Ω, its reading when fed by 250 V, 50 Hz ac will be
260 V
252 V
250 V
248 V
Your Answer: Option
(Not Answered)
Correct Answer: Option
Explanation:


5.
In a half bridge inverter each thyristor is gated at a frequency f. The output frequency is
2 f
f
0.5 f
0.25 f
Your Answer: Option
(Not Answered)
Correct Answer: Option

6.
Ultra high frequency oscillators work in the range
20 Hz to 20 kHz
1 kHz to 30 kHz
30 kHz to 30 MHz
above 30 MHz
Your Answer: Option
(Not Answered)
Correct Answer: Option

7.
The voltage gains of an amplifier without feedback and with negative feedback respectively are 100 and 20. The percentage of negative feedback would be.
40%
5%
20%
80%
Your Answer: Option
(Not Answered)
Correct Answer: Option

8.
If 4 in binary system is 100 then 8 will be
10
100
111
1000
Your Answer: Option
(Not Answered)
Correct Answer: Option

9.
Consider the following statements about loop antenna
  1. It is suitable for direction finding application
  2. It is a single turn or multiturn coil carrying RF current
  3. The loop is surrounded by a magnetic field everywhere perpendicular to the loop
Which of the above statements are correct?
1 and 2 only
1 only
1, 2, 3
2 and 3 only
Your Answer: Option
(Not Answered)
Correct Answer: Option
Explanation:

All the three are correct.


10.
If a line is terminated in characteristic impedance Z0, the input impedance measured at the input will be
Z0
Z0/2
Zero
infinite
Your Answer: Option
(Not Answered)
Correct Answer: Option
Explanation:

If line is terminated in Z0, the input impedance is Z0.


11.
A device with input x(t) and y(t) is characterized by y(t) = x2(t). An FM signal with frequency deviation of 90 kHz and modulating signal bandwidth of 5 kHz is applied to this device. The bandwidth of the output signal is
370 kHz
190 kHz
380 kHz
95 kHz
Your Answer: Option
(Not Answered)
Correct Answer: Option
Explanation:

If we square the signal, bandwidth will becomes double.

B.W. for x(t) = 2(90 + 5) = 190 kHz

for x2(t) = 2 x 190 380 kHz.


12.
The modulation index of a narrowband FM signal is
nearly equal to 0.3
much less than unity
nearly 0.5
much more than unity
Your Answer: Option
(Not Answered)
Correct Answer: Option

13.
An image uses 512 x 512 picture elements. Each element can take any of eight distinguishable levels. The maximum entropy in the above image will be
2097152 bits
786432 bits
648 bits
144 bits
Your Answer: Option
(Not Answered)
Correct Answer: Option

14.
In an FM signal, the power
increases as the modulation index increases
reduces as the modulation index increase
increases as the modulation index decreases
remains constant when the modulation index increases
Your Answer: Option
(Not Answered)
Correct Answer: Option

15.
Which of the following real expressions is correct in Pascal?
- Z + P * X
(X + Y) (A + B)
Z ** M
Z P * M
Your Answer: Option
(Not Answered)
Correct Answer: Option
Explanation:

All others are incorrect.


16.
The number of registers and flags in 8086 are
13 and 5 respectively
9 and 5 respectively
13 and 9 respectively
9 and 9 respectively
Your Answer: Option
(Not Answered)
Correct Answer: Option

17.
In 8085, high level on INTR line can be recognised only if
TRAP and RST lines are high
TRAP and RST lines are not high
TRAP line is high but not RST line
RST line is high but not TRAP line
Your Answer: Option
(Not Answered)
Correct Answer: Option

18.
Given L[f(t)] = and L[g(t)] = also h(t) = , where, x = then, L[h(t)] = __________ .
Your Answer: Option
(Not Answered)
Correct Answer: Option
Explanation:

Now, x =

log x = ejp x log S log x = y,

x = ey

log x = log Sejp

x = Sejp

x = S-1

L[f(t)] = L[f(t)] x L[g(t)].


19.
The electric field of 2.5 x 107 V/m can give 1 eV energy to condition electron, then in a copper block what will be the mean free path of electron?
5 x 10-8 m
4 x 10-7 m
0.4 m
0.5 m
Your Answer: Option
(Not Answered)
Correct Answer: Option
Explanation:

The force on electron in eE. As the electron moves through distance d , the work done on it is eEd.

This is equal to energy transferred to electron.

eEd = 1 eV

d = 4 x 10-7m.


20.
Which one of the following is used as the interface chip for data transmission between 8086 and a 16-bit ADC?
8259
8255
8253
8251
Your Answer: Option
(Not Answered)
Correct Answer: Option

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