Interview questions

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SNS COLLEGE OF ENGINEERING, COIMBATORE
DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
WRITTEN TEST
1. The output Qn of a J-K flip-flop is zero. It changes to 1 when a clock pulse is applied. The
Inputs Jn and Kn are respectively.
(a) 1 and X (b) 0 and X (c) X and 0 (d) X and 1
2. The number of bits needed to address 4K memory is
(a) 6 (b) 8 (c)12 (d) 16
3. The main advantage of flip-flops over transistor circuit is
(a) Immunity from noise (b) Low heating
(c) Low propagation delay time (d) High propagation.
4. How many bits does one need to encode all twenty-six letters, ten symbols, and ten
Numerals?
(a) 5 (b) 6 (c) 7 (d) 46
5. The total number of Boolean functions which can be realized with your variables is
(a) 4 (b)16 (c) 256 (d) 65,536
6. In a 16-bit microprocessor, words are stored in two consecutive memory locations. The entire word can be
read in one operation provided the first
(a) Word is even (b) Word is odd
(c) Memory location is odd (d) Memory address is even
7. Which logic circuit is the fastest?
(a) TTL (b) DTL (c) RTL (d) all has same speed
8. Which of the following sets represents a universal logic family?
(a) NAND (b) XOR (c)NAND (d) None of the above
9. The Boolean expression (A+C÷D) (B+D+C) may be simplified as
(a) AB + CB (b)AB+C+÷D (c) A+BC+D (d) A+B+CD

10. The maximum propagation value in case of 7400 NAND gates is
(a) 1 second (b) 20 milliseconds
(c) Less than 20 nanoseconds (d) Less than 20 picoseconds
11. Single-element semiconductors are characterized by atoms with ____ valence electrons.
(a) 3 (b) 4 (c) 5 (d) 2
12. A one-to-sixteen demultiplexer requires
(a) 2 select input lines. (b) 3 select input lines.
(c) 8 select input lines. (d) 4 select input lines.
13. The number of states in its counting sequence that a ring counter consisting of ‘n’ flip-flops can have is
(a) 2n
− 1 (b) 2n −1
(c) n (d) 2n +1
14. In a transistor amplifier, the reverse saturation current ICO
(a) double for every 10Degree rise in temperature
(b) doubles for every 1Degree rise in temperature
(c) increase linearly with the temperature
(d) doubles for every 5Degree rise in temperature
15. The emitter of the transistor is generally doped the heaviest because it
(a) has to dissipate maximum power (c) is the first region of transistor
(b) has to supply the charge carriers (d) must possess low resistance
16. A transistor when connected in CE mode has
(a) a low input resistance and a low output resistance
(b) a high input resistance and high output resistance
(c) a high input resistance and low output resistance
(d) a medium input resistance and high output resistance
17. The pinch off voltage is the voltage
(a) At which gate source junction breaks down
(b) Which causes depletion regions to meet
(c) The voltage applied between drain & source
(d) Neither of these
18. If properly biased JFET acts as
(a) Current controlled current source
(b) Voltage controlled voltage source
(c) Voltage controlled current source
(d) Current controlled voltage source
19. A transconductance amplifier has
(a) High input impedance and low output impedance
(b) Low input impedance and high output impedance
(c) High input and output impedances
(d) Low input and output impedances

20. A JFET is similar is operation to
(a) Diode (c) Triode
(b) Pentode d. Tetrode
21. A cascode amplifier has the advantage of
(a) Large voltage gain (b) Low input impedance
(b) Low input capacitance (d) High gm
22. Avalanche breakdown in a diode occurs when
(a) Potential barrier is reduced to zero.
(b) Forward current exceeds certain value.
(c) Reverse bias exceeds a certain value.
(d) None of these
23. In the diode equation, the voltage equivalent of temperature is
(a) 11600/T (b) T/11600 (c) T X 11600 (d) 11600/T2
24. When a reverse bias is applied to a diode, it will
(a) Raise the potential barrier
(b) Lower the potential barrier
(c) Increases the majority-carrier a current greatly
(d) None of these
25. Bandwidth of FM signal is —than AM signal
(a) lesser (b) either lesser or larger (c) larger (d) none of these
26. In FM modulation, when the modulation index increases,transmitted power is
(a) constant (b) increased (c) decreased (d) none of these
27. An older type of data communications channel, using multiple copper wires, is called ________
technology.
a) Microwave b) fiber-optic cable c) coaxial cable d) twisted pair
28. An energy signal has G(f) = 10. Its energy density spectrum is
(a) 10 (b) 100 (c) 50 (d) 20
29. Which one is a linear system?
(a) y[n] = x[n] x x[n - 1] (b) y[n] = x[n] + x[n - 10]
(c) y[n] = x2
[n] (d) (a) and (c)
30. δ(t) is a
(a) energy signal (b) power signal (c) neither energy nor power (d) none
31. The Laplace transform of a unit step function is
(a) 1 (b) 1 / s (c) s (d) 1 / s2

32. The inverse Fourier transform of δ(t) is
(a) ∪(t) (b) 1 (c) δ(t) (d) ej2pt
33. VSB modulation is preferred in TV because
(a) it reduces the bandwidth requirement to half
(b) it avoids phase distortion at low frequencies
(c) it results in better reception
(d) none of the above
34. The distance of a direct broadcasting satellite from earth's surface is about
(a)
1000 km (b) 10000 km (c) 36000 km (d) 55000 km
35. UHF range is
(a) 3 to 30 MHz (b) 30 to 300 MHz (c) 300 to 3000 MHz (d) 3000 to 30000 MHz
36. Binary number 1101.101 is equivalent to decimal number?
(a) 13.5 (b)13.75 (c) 13.625 (d) 13.875
37. The different access methods which permit many satellite users to operate in parallel through a single transpond
without interfering with each other as
(a) Frequency Division Multiple Access (FDMA)
(b) Time Division Multiple Access (TDMA)
(c) Code Division Multiple Access (CDMA)
(d) All of the above
38. A loss less line of characteristic impedance Z0 is terminated in pure reactance of -jZ0value. VSWR is
(a) 10 (b) 2 (c) 1 (d) Infinity
39. Which of the following lines is non-radiating?
(a) Open two wire (b) Coaxial (c) Both (d) None of the above
40. A quarter wave line open circuited at far end behaves as
(a) Inductance (b) L and C in parallel
(c)
Capacitance (d) L and C in series

41. A train running at the speed of 60 km/hr crosses a pole in 9 seconds. What is the length of the train?
(a) 120 metres (b) 180 metres (c) 324 metres (d) 150 metres
42. In the first 10 overs of a cricket game, the run rate was only 3.2. What should be the run rate in the
remaining 40 overs to reach the target of 282 runs?
(a) 6.25 (b) 6.5 (c) 6.75 (d) 7
43. If one-third of one-fourth of a number is 15, then three-tenth of that number is:
(a) 35 (b) 36 (c) 45 (d) 54
44. What decimal of an hour is a second?
(a) .0025 (b) .0256 (c)
.00027 (d) .000126
45. Two students appeared at an examination. One of them secured 9 marks more than the other and his
marks was 56% of the sum of their marks. The marks obtained by them are:
(a) 39, 30 (b) 41, 32 (c) 42, 33 (d) 43, 34
46. Which one of the following is the main objective of the “Green India Mission”?
(a) To enhance carbon sinks through large scale afforestation
(b)To enhance the utilisation of renewable energy
(c)To promote organic farming by reducing use of fertilisers
(d)To phase out use of greenhouse gas
47. Ayesha always ...... the permission of her father before going for movies.
(a) seeking (b) seeks (c) sought (d) seeker
48. One Gigabyte is approximately equal is
(a) 1000,000 bytes (b) 1000,000,000 bytes (c) 1000,000,000,000 bytes
(d) None of these
49. What is the name of Google’s new project which intends to provide high speed broadband internet
connection in selected cities?
(a) Google Net (b) Google Fiber (c) Google Demo (d) Google Connect
50. B2CD, _____,BCD4,B5CD,BC6D
(a) B2C2D (b) BC3D (c) B2C3D (d) BCD7

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