# RRB - Railway Recruitment Board Exam Model Question Papers - Part 3

RRC/RRB Exam Questions and Answers - Part 3

1. The forward resistance of crystal will be _____ than its reverse resistance.
(A) Much higher (B) Much less (C) Equal (D) Medium

2. The full scale deflection of ohm scale in a multimeter reads
(A) Zero (B) Infinite (C) Maximum (D) Minimum

3. Positive feedback is used in
(A) High gain amplifier (B) Low gain amplifier (C) Oscillator (D) Simple gain amplifier

4. If emitter current in a transistor is 1MA, then the collector current is
(A) 1.8 MA (B) 1 MA (C) 1Âµ A (D) 2 MA

5. Reverse resistance of a diode is of the order of
(A) K ohm's (B) Ohm's (C) Mega ohm's (D) Âµ ohm's

6. R. C. coupling is used for amplification of the
(A) Current (B) Resistance (C) Power (D) Voltage

7. In super hetrodyne radio receiver, the mixer stage produces an intermediate frequency of
(A) 475 KHZ (B) 55 KHZ (C) 455 KHZ (D) 500 KHZ

8. The addition of pentavalent impurity to a semiconductor creates
(A) Holes (B) Free electrons (C) Minority electrons (D) Majority electrons

9. In a semiconductor, the energy gap between valence band and conduction band is
(A) 15 ev (B) 5 ev (C) lev (D) 7 ev

10. In full wave rectifier if the input frequency is 50 HZ, then the output frequency is
(A) 50 HZ (B) 100 HZ (C) 200 HZ (D) 400 HZ

11. A zener diode is used as a
(A) Rectifier (8) Break down voltage (C) Voltage regulator (D) Forward characteristic

12. The maximum efficiency of full wave rectifier is
(A) 40 (B) 81.2 (C) 90 (D) 98

13. With the rise in temperature of a P-N juncti0n, which of the following will increase?
(A) Width of depletion layer (B) Junction barrier voltage (C) Reverse leakage current (D) All of these

14. A PNP transistor is made of
(A) Germanium (B) Silicon (C) Either germanium or silicon (D) None of these

15. Which of the following is the fastest switching device?
(A) BJT (B) JFET (C) MOSFET (D) Tridoe

16. Three cascaded stages have gains of 1O, 2O and 25. The overall gain will be
(A) 5000 (B) 500 (C) 55 (D) 10

17. Which class of amplifier has the least distortion?
(A) AB (B) C (C) B (D) A

18. A pulse transformer uses
(A) Copper core (B) Iron core (C) Ferrite core (D) Air core

19. The third harmonic of 300 Hz is
(A) 160 Hz (B) 300 Hz (C) 900 Hz (D) 2700 Hz

20. A triac a is like
(A) NPN transistor (B) PNP transistor (C) Unidirectional SCR (D) Bidirectional SCR

21. A thyristor is often used in
(A) Wall clocks (B) Digital multimeters (C) Speed control of motors (D) All of these

22. Which of the following is the most stable oscillator?
(A) Wein bridge oscillator (B) Colpitts oscillator (C) Hartley oscillator (D) Crystal controlled oscillator

23. The calibration signal, usually available from a CRO, is of the
(A) Sine-wave voltage (B) Square-wave voltage (C) Saw tooth-wave voltage (D) D.C voltage

24. In which of the following microphone backgrounds, noise is present?
(A) Crystal microphone (B) Condenser microphone (C) Ribbon microphone (D) Carbon microphone

25. What should be the oscillator frequency for tuning in 710 KHz on an AM radio with a 455 KHz IP?
(A) 127.5 KHz (B) 255 KHz (C) 1165 KHz (D) 2330 KHz

26. In TV system
(A) Picture is AM, sound is FM (B) Picture is FM, sound is AM (C) Picture and sound both are AM (D) Picture and sound both are FM

27. In TV, to eliminate ghosts in the picture
(A) Longer transmission line should be connected (B) A booster should be connected (C) Antenna orientation should be changed (D) None of these

28. In telephone, the dial tone has a frequency of
(A) 1 Hz (B) 13 Hz (C) 33 Hz (D) 133 Hz

29. A device that converts from decimal number to a binary number is called
(A) CPU (B) Decoder (C) Converter (D) Encoder

30. Which logic gate is similar to the function of two series switches?
(A) OR (8) NAND (C) AND (D) All of these