# RRB - Railway Recruitment Board Exam Model Question Papers - Part 1

RRB Exam Questions and Answers - Part 1

1. Which type of insulation material's category bears the maximum temperature?
A) A category B) B category C) C category D) E category

2. An electrical heater takes 1000 watt at 250 volt supply. At half the resistance and 20 volt supply, how much power it takes?
A) 1680 Watt B) 80 Watt C) 1280 Watt D) 680 Watt

3. The potential of the hallow circle is
A) Zero B) Equal to outer surface C) Greater than the outer surface D) Less than the outer surface

4. A fully-charged lead acid battery has which of the following active materials at the negative and positive plates?

5. The speed of D. C. motor is
(A) Always constant B) Directly proportional to flux C) Directly proportional to back e.m.f. D) Universally proportional to E and flux

6. If power factor of a load is low at c0nstant load, then
A) It will take maximum current B) It will take less current C) The current is same but power factor is low D) It will take less current but power factor is high

7. In polyphase system, the phase differences are always equal to
A) 1200° B) 90° (C) 360°/No. of phases D) None of these

8. In which part of the transformer, the maximum heat is produced?
A) Core B) Oil C) Windings D) Frame

9. Difference between the synchronous speed and the induction motor speed is called
A) Regulation B) Slip C) Back lash D) Lag

10. To measure the higher current which instrument is used?
A) Potential transformer B) Induction type meter C) Current transformer D) Repulsion type meter

11. Which rectifier requires four diodes?
A) Voltage quadrupler B) Full-wave rectifier C) Full-wave bridge rectifier D) Half-wave rectifier

12. The primary function of a rectifier filter is
A) Minimise A.c. input variations B) Suppress odd harmonics in the rectifier output C) Stabilise d.c. level of the output voltage D) Remove ripples from the rectified output

13. The resistance of a 100 watt. Then 230 V lamp is
A) 52.9 Ω B) 529 Ω C) 2.3 Ω D) None of these

14. A wire has a resistance of 10 ohms. The resistance of another wire of the same material, four times as long as the first wire and one half of the cross secti0nal area, will be
A) 40 Ω B) 60 Ω C) 80 Ω D) 20 Ω

15. If a 1000 W heater is used for 5 hours, then the cost of energy @ Rs.1.50 per unit will be
A) Rs. 225 B) Rs. 15 (C) Rs. 1.50 (D) Rs. 7.50

16. The time period of sinusoidal wave at standard frequency in India is
A) 1 second B) 0.1 second C) 0.2 second D) 0.02 second

17. A coil having a resistance of 60 ohms and inductive reactance of 80 ohms is connected across 240V, 50 Hz supply. The power factor of the coil will be
A) 0.8 B) 0.6 C) Unity D) Zero

18. In balanced 3 Ф supply system, the current in the neutral is equal to
A) Phase current B) Line current C) X phase current D) Zero

19. The resistance of shunt winding of a d. c. machine may be about
A) 200 ohms B) 25 ohms C) 1 ohm D) 0.5 ohm

20. How many parallel paths will be there in an eight-pole wave-connected
armature of a d. c. machine?
A) 12 B) 4 C) 8 D) 2

21. The e. m. f. generated by a d. c. generator depends upon
A) Its speed B) Flux per pole C) Flux and speed both D) None of these

22. A 200V, d. c. shunt motor has armature resistance of 0.5 ohm. If no- load armature current is 2A, then the value of back e.m.f. will be
A) 200 volts B) 201 volts C) 199 volts D) 190 volts

23. The no-load power factor of a transformer may be

24. Core of the transformer is made of
A) Iron B) Coper C) Low silicon steel D) High silicon steel

25. The open circuit test at rated voltage is performed on a transformer to determine its
A) Regulation B) Efficiency C) Iron losses D) Copper losses

26. Three-phase distribution transformer's connections are
(A) Star-star (B) Delta-delta (C) Star-delta (D) Delta-star

27. The rotating magnetic field of the stator of induction motor rotates relative
to the core at a speed of
A) N3 B) N2 C) SN3 D) SN2

28. A universal motor is
A) 1 Ф a.c. motor B) A d.c. motor C) Both a.c. & d.c. motor (D) 3 Ф a.c. motor

29. Which of the following motors is best suited for ceiling fan?
A) Capacitor run motor B) Split phase motor C) Shaded pole motor D) Reluctance motor

30. The maximum speed of a synchronous machine at 50 Hz frequency is
A) 2000 r.p.m. B) 3000 r.p.m. C) 1500 r.p.m. D) 3600 r.p.m.