Electronic Engineering MCQ Question Papers: ENTC, IT Interview Placement

Q1. An earth mat for a communication tower consists of

a) One or two radials extending from base of tower at a depth of about 5 cm below ground

b) A large number of radials extending from base of tower at a depth of about 3 m

c) a large number of radials extending from base of tower at a depth of about 30 cm

d) None of the above

Q2. Degaussing in a picture tube means

b) Removing residual magnetism in mask, shield etc…

c) Increasing resistance of coils to decrease time constant

d) Decreasing resistance of coils to increase time constant

Q3. The rate at which information can be carried through a communication channel depends on

a) Carrier frequency

b) bandwidth

c) Transmission loss

d) Transmitted power

Q4. Some types of traps used in video if amplifier of colour tv are

a) Shunt traps

b) Series traps

c) Absorption traps

d) all of the above

Q5. A carrier is simultaneously modulated by two sine waves having modulation indices of 0.4 and 0.3. The total modulation index will be

a) 0.1

b) 0.7

c) 0.5

d) 0.35

Q6. A 1000 khz carrier is simultaneously modulated with 300 hz, 800 hz and 2 khz audio sine waves. Which of the following frequency is least likely to be present in the output?

a) 1002 khz

b) 1000 khz

c) 999.2 khz

d) 998.0 khz

Q7. In standing wave pattern on a transmission line

a) Voltage and current nodes coincide

b) Voltage and current antinodes coincide

c) voltage nodes and current antinodes as well as current nodes and voltage antinodes

coincide

d) Both (a) and (b)

Q8. If the bandwidth is increased by 2, the yfm and yam (where y is the ratio of SNR of output to SNR at input, fm is frequency modulation and am is amplitude modulation) is increased by a factor of

a) 2

b) 3

c) 4

d) 6

Q9. Frequency shift keying is used mostly in

a) telegraphy

b) Telephony

c) Satellite communication

Q10. It is desired that transmission line and load should match for a range of frequencies. The best method is

a) To use a balun

b) To use a single stub of adjustable position

c) to use a double stub

d) To use a broad band amplifier

Q11. Which of the following has the highest input impedance?

a) Ce

b) Cb

c) cc

d) Push pull

Q12. In a fascimile reproduction time to scan one line is 2 ms. If it has 4% blanking, the visible trace time is

a) 1.92 ms

b) 2.08 ms

c) 50 ms

d) 0.08 ms

Q13. Signal to noise ratio of microphone is defined as the ratio of output when the sound pressure is __________ to the output in the absence of any sound signal

a) 0.5 pa

b) 0.2 pa

c) 0.1 pa

d) 0.01 pa

Q14. Atransmission generator is feeding power to a line of characteristic impedance z0. The line is terminated in impedance zl. Standing waves will be set up if

a) Zl = z0

b) Zl is less than z0

c) Zl is greater than z0

d) both (b) and (c)

a) Amplitude modulation

b) frequency modulation

c) Both amplitude and frequency modulation

d) Neither amplitude nor frequency modulation

Q16. If the frequency of a wave 20 hz, the time period is

a) 20 secs

b) 2 secs

c) 0.2 secs

d) 0.05 secs

Q17. Which of the following is taken as reference antenna for directive gain?

a) Half wave dipole

b) Elementary doublet

c) isotropic

d) Infinitesimal dipole

Q18. Push pull amplifier is

a) Voltage amplifier

b) Current amplifier

c) power amplifier

d) None of the above

Q19. When the channel is noisy, producing a conditional probability of error p = 0.5; the channel capacity and entropy function would be, respectively,

a) 1 and 1

b) 1 and 0.5

c) 0.5 and 1

d) 0 and 1

Q20. In ccir-b system, the time between start of one h syn. Pulse and next is

a) 64 us

b) 6.4 us

c) 640 us

d) 0.64 us