SPSC 2013 Planning Officer (Energy Section) BPS-17, P&D Department (2013) — Electronics Engineering, Paper Type B Paper

Planning Officer (Energy Section) BPS-17, P&D Department (2013) — Electronics Engineering, Paper Type B. Pre-interview written test · Tuesday 24 December 2013, 10:00 am to 11:00 am · Maximum marks 100. 50 MCQs; each incorrect answer deducts half mark.

1. 1The ac equivalent circuit is derived from the original circuit by shorting all

   • A)Resistors
   • B)Capacitors
   • C)Inductors
   • D)Transistors

   Explanation: (and reducing the dc sources to zero).

2. 2The input impedance of the base increases when

   • A)β increases
   • B)Supply voltage increases
   • C)β decreases
   • D)AC collector resistance increases

3. 3Compared to a CE stage, a swamped amplifier has an input impedance that is

   • A)Smaller
   • B)Equal
   • C)Larger
   • D)Zero

4. 4The third round table conference was held in;

   • A)1930
   • B)1932
   • C)1934
   • D)1933

5. 5The Federal Shariat court was established in;

   • A)24th June 1980
   • B)22nd June 1980
   • C)25th June 1980
   • D)None of these

   Explanation: It was set up by President's Order in May 1980 (functioning from 28 May 1980).

6. 6At high frequencies, ordinary diodes don't work properly because of

   • A)Forward bias
   • B)Reverse bias
   • C)Breakdown
   • D)Charge storage

7. 7A photodiode is normally

   • A)Forward biased
   • B)Reverse biased
   • C)Neither forward nor reverse biased
   • D)Emitting light

8. 8The device associated with voltage-controlled capacitance is a

   • A)LED
   • B)Photodiode
   • C)Varactor diode
   • D)Zener diode

9. 9In an npn transistor, the majority carriers in the base are

   • A)Free electrons
   • B)Holes
   • C)Neither
   • D)Both

10. 10The current gain of a transistor is the ratio of the

    • A)Collector current to emitter current
    • B)Collector current to base current
    • C)Base current to collector current
    • D)Emitter current to collector current

11. 11The bulk resistance of a 1N4001 is

    • A)0
    • B)0.23 Ω
    • C)10 Ω
    • D)1 kΩ

12. 12Suppose line voltage may be as low as 105 V rms or as high as 125 V rms in a half-wave rectifier. With a 5:1 step-down transformer, the maximum peak load voltage is closest to

    • A)21 V
    • B)25 V
    • C)29.6 V
    • D)35.4 V

    Explanation: 125 ÷ 5 = 25 V rms; × 1.414 = 35.4 V peak.

13. 13If line frequency is 60 Hz, the output frequency of a bridge rectifier is

    • A)30 Hz
    • B)60 Hz
    • C)120 Hz
    • D)240 Hz

14. 14If the filter capacitance is increased, the ripple will

    • A)Decrease
    • B)Stays the same
    • C)Increases
    • D)None of these

15. 15If the series resistance decreases in an unloaded Zener regulator, the Zener current

    • A)Decreases
    • B)Stays the same
    • C)Increases
    • D)Equals the voltage divided by the resistance

16. 16An ideal voltage source has

    • A)Zero internal resistance
    • B)Infinite internal resistance
    • C)A load-dependent voltage
    • D)A load-dependent current

17. 17A solder bridge may cause

    • A)A short
    • B)An open
    • C)A fire
    • D)A Norton current

18. 18The quiescent collector current is the same as the

    • A)DC collector current
    • B)AC collector current
    • C)Total collector current
    • D)Voltage-divider current

19. 19If a load resistance is 1 kΩ, a stiff current source has a resistance of

    • A)At least 10 Ω
    • B)Less than 10 Ω
    • C)More than 100 kΩ
    • D)Less than 100 kΩ

20. 20If clipping occurs in an amplifier, it makes music or voice

    • A)Sound better
    • B)Louder
    • C)Sound terrible
    • D)One octave lower

21. 21Give the date of arrival of Simon Commission in India?

    • A)3rd November 1928
    • B)3rd December 1928
    • C)3rd February 1928
    • D)None of these

22. 22When was the Radcliffe award announced: (a) 15 August 1948 (b) 15 August 1947 (c) 15 August 1949 (d) 18 August 1945

    Answer: None of the printed dates is right: the Radcliffe Award was published on 17 August 1947.

23. 23When was Liaquat Ali Khan assassinated?

    • A)17 October 1951
    • B)16 October 1951
    • C)18 October 1951
    • D)None of these

24. 24Which is the largest desert in the world.

    • A)Arabian
    • B)Australian
    • C)Sahara
    • D)Gobi

    Explanation: The Sahara is the largest hot desert.

25. 25The longest river of the world is

    • A)Nile
    • B)Lena
    • C)Parana
    • D)Congo

26. 26Which one is the largest Island in the world

    • A)Borneo
    • B)Great Britain
    • C)Victoria
    • D)Greenland

27. 27Jinnah's famous fourteen points were formulated in;

    • A)March 1923
    • B)March 1924
    • C)March 1925
    • D)March 1929

28. 28When Muhammad Bin Qasim Defeated Raja Dahar;

    • A)712
    • B)713
    • C)715
    • D)718

29. 29Name the leader who took active part in forming Muslim League in Baluchistan

    • A)Qazi Muhammad Isa
    • B)Qazi Muhammad Moosa
    • C)Qazi Saeed
    • D)Ghulam Muhammad Chowdhray

30. 30When was Pakistan Conference Held in Islamiya College Lahore?

    • A)1942
    • B)1941
    • C)1940
    • D)None of these

    Explanation: The Punjab Muslim Students Federation's Pakistan Conference, March 1941.

31. 31With voltage-divider bias, the base voltage is

    • A)Less than the base supply voltage
    • B)Equal to the base supply voltage
    • C)Greater than the base supply voltage
    • D)Greater than the collector supply voltage

32. 32The voltage where avalanche occurs is called the

    • A)Barrier potential
    • B)Depletion layer
    • C)Knee voltage
    • D)Breakdown voltage

33. 33When the reverse voltage increases from 5 to 10 V, the depletion layer

    • A)Becomes smaller
    • B)Becomes larger
    • C)Is unaffected
    • D)Breaks down

34. 34When the graph of current versus voltage is a straight line, the device is referred to as

    • A)Active
    • B)Linear
    • C)Nonlinear
    • D)Passive

35. 35The leakage current consists of minority-carrier current and

    • A)Avalanche current
    • B)Forward current
    • C)Surface-leakage current
    • D)Zener current

36. 36How much current is there through the second approximation of a silicon diode when it is reverse-biased?

    • A)0
    • B)1 mA
    • C)300 mA
    • D)None of the above

37. 37Norton's theorem replaces a complicated circuit facing a load by an

    • A)Ideal voltage source and parallel resistor
    • B)Ideal current source and parallel resistor
    • C)Ideal voltage source and series resistor
    • D)Ideal current source and series resistor

38. 38How many valence electrons does a silicon atom have?

    • A)0
    • B)1
    • C)2
    • D)4

39. 39An intrinsic semiconductor has some holes in it at room temperature. What causes these holes?

    • A)Doping
    • B)Free electrons
    • C)Thermal energy
    • D)Valence electrons

40. 40Silver is the best conductor. How many valence electrons do you think it has?

    • A)1
    • B)4
    • C)18
    • D)29

41. 41What is the barrier potential of silicon diode at room temperature?

    • A)0.3 V
    • B)0.7 V
    • C)1 V
    • D)2 mV per degree Celsius

42. 42With VDB, an increase in emitter resistance will

    • A)Decrease the emitter voltage
    • B)Decrease the collector voltage
    • C)Increase the emitter voltage
    • D)Decrease the emitter current

    Explanation: The emitter voltage is fixed by the divider, so a larger RE means less emitter current.

43. 43Base bias is associated with

    • A)Amplifiers
    • B)Digital circuits
    • C)Stable Q point
    • D)Fixed emitter current

    Explanation: Base bias is used mainly in switching (digital) circuits.

44. 44If the emitter resistor opens with the TSEB, the collector voltage will

    • A)Decrease
    • B)Stay the same
    • C)Increase slightly
    • D)Equal the collector supply voltage

45. 45For dc, the current in a coupling circuit is

    • A)Zero
    • B)Maximum
    • C)Minimum
    • D)Average

46. 46A capacitor is

    • A)A dc open
    • B)An ac short
    • C)A dc short and an ac open
    • D)A dc open and an ac short

47. 47The base-emitter voltage of an ideal transistor is

    • A)0
    • B)0.3 V
    • C)0.7 V
    • D)1 V

48. 48Ignoring the bulk resistance of the collector diode, the saturation voltage is

    • A)0
    • B)A few tenths of a volt
    • C)1 V
    • D)Supply voltage

49. 49If a transistor operates at the middle of the load line, an increase in the base resistance will move the Q point

    • A)Down
    • B)Up
    • C)Nowhere
    • D)Off the load line

50. 50A circuit with a fixed emitter current is called

    • A)Base bias
    • B)Emitter bias
    • C)Transistor bias
    • D)Two-supply bias