Part VII — Practice

Chapter 7: Mixed Practice Set — All Technical Topics (50 MCQs)

This chapter mixes questions from every technical chapter in this book, in exam-realistic random order.

1. Ohm's Law states that, at constant temperature:
   (a) V = I/R (b) V = IR (c) V = I + R (d) V = I²R only
2. Kirchhoff's Current Law (KCL) is based on conservation of:
   (a) Energy (b) Charge (c) Momentum (d) Mass alone
3. Kirchhoff's Voltage Law (KVL) is based on conservation of:
   (a) Charge (b) Energy (c) Momentum (d) Mass
4. In a series circuit, total resistance is:
   (a) The sum of individual resistances (b) The reciprocal of the sum of reciprocals (c) Always less than the smallest resistance (d) Always zero
5. Thevenin's Theorem replaces a linear network with:
   (a) A current source in parallel with a resistance (b) A voltage source in series with a resistance (c) Two voltage sources in parallel (d) A pure resistance only
6. Maximum power transfer to a load occurs when load resistance equals:
   (a) Zero (b) Infinity (c) The source's Thevenin resistance (d) Twice the source resistance
7. For a pure sine wave, RMS value relates to peak value by:
   (a) RMS = Peak × 2 (b) RMS = Peak / √2 (c) RMS = Peak × π (d) RMS = Peak / 2
8. The standard AC supply frequency in India is:
   (a) 25 Hz (b) 50 Hz (c) 60 Hz (d) 100 Hz
9. A series DC motor is characterised by:
   (a) Very high starting torque but poor speed regulation (b) Constant speed regardless of load (c) No starting torque (d) Only fan applications
10. A shunt DC motor is best suited for applications requiring:
    (a) High starting torque with variable speed (b) Relatively constant speed regardless of load (c) No speed control (d) Intermittent operation only
11. In an ideal transformer, the transformation ratio V2/V1 equals:
    (a) N1/N2 = I2/I1 (b) N2/N1 = I1/I2 (c) N1×N2 (d) I1×I2
12. Maximum transformer efficiency occurs when:
    (a) Copper losses are zero (b) Iron losses are zero (c) Copper losses equal iron losses (d) Copper losses are always twice iron losses
13. Transformer cores are laminated primarily to reduce:
    (a) Copper losses (b) Eddy current losses (c) Hysteresis losses only (d) Magnetic flux entirely
14. Slip in an induction motor is defined as:
    (a) (Ns + Nr)/Ns (b) (Ns − Nr)/Ns (c) Ns/Nr (d) Nr/Ns
15. Synchronous speed (Ns) is given by:
    (a) Ns = 120f/P (b) Ns = f/120P (c) Ns = P/120f (d) Ns = 120P/f
16. A synchronous motor, unlike an induction motor, is generally:
    (a) Self-starting under all conditions (b) Not self-starting, requiring external methods (c) Unable to run at synchronous speed (d) Only usable as a generator
17. Which type of power plant has historically been India's dominant electricity source?
    (a) Nuclear (b) Hydroelectric (c) Thermal (predominantly coal-based) (d) Solar
18. Electrical power is transmitted at high voltage primarily to:
    (a) Increase current (b) Reduce current and I²R losses (c) Simplify transformers only (d) Avoid substations
19. HVDC transmission is particularly advantageous for:
    (a) Short-distance urban distribution (b) Very-long-distance/bulk point-to-point transmission (c) Household wiring (d) Low-voltage applications only
20. A circuit breaker, compared to a fuse, is generally:
    (a) A one-time-use device (b) A reusable switching device operated via a relay (c) Incapable of interrupting fault currents (d) Only for household wiring
21. Power factor is defined as:
    (a) The ratio of reactive power to real power (b) The cosine of the phase angle between voltage and current (c) The square of voltage (d) The ratio of current to voltage
22. Power factor improvement is commonly achieved using:
    (a) Additional resistors (b) Capacitor banks (c) Additional transformers only (d) Higher-voltage lines only
23. An ammeter is always connected in a circuit:
    (a) In parallel (b) In series (c) Neither (d) Only across source terminals
24. A voltmeter is always connected in a circuit:
    (a) In series (b) In parallel (c) Only in a bridge configuration (d) Directly across the ammeter
25. A wattmeter combines which two elements?
    (a) Two current coils (b) Two voltage coils (c) A current coil (series) and a voltage coil (parallel) (d) A single resistor
26. Moving Coil (PMMC) instruments work only on:
    (a) AC (b) DC (c) Both AC and DC equally (d) Neither
27. Moving Iron (MI) instruments can work on:
    (a) DC only (b) AC only (c) Both AC and DC (d) Neither
28. A Megger is specifically used to measure:
    (a) Power factor (b) Insulation resistance (c) Frequency (d) Energy consumption
29. Household energy meters measure energy consumption in:
    (a) Watts (b) Kilowatt-hours (kWh) (c) Amperes (d) Volts
30. A semiconductor's conductivity lies between that of:
    (a) Two insulators (b) A conductor and an insulator (c) Two conductors (d) A superconductor and conductor
31. N-type semiconductors are created by doping with:
    (a) Trivalent impurities (b) Pentavalent impurities (c) No impurities (d) Only metallic impurities
32. A PN junction diode, in forward bias (silicon), conducts once voltage exceeds approximately:
    (a) 0.1V (b) 0.7V (c) 5V (d) 12V
33. A BJT has how many terminals?
    (a) Two (b) Three (c) Four (d) Five
34. In a BJT, a small base current controls:
    (a) A much larger collector-emitter current (b) Only base voltage (c) Nothing (d) Only leakage current
35. An open-loop control system is characterised by:
    (a) Continuous feedback (b) No feedback; output has no influence on control action (c) Always higher accuracy than closed-loop (d) Requiring a comparator
36. A thermostat-controlled heating system is an example of:
    (a) An open-loop system (b) A closed-loop (feedback) system (c) Neither (d) A purely mechanical system with no control
37. Resistance of a conductor (R = ρL/A) increases with:
    (a) Increasing length (b) Increasing cross-sectional area (c) Decreasing length (d) Decreasing resistivity
38. For two resistors in parallel, the equivalent resistance is:
    (a) R1 + R2 (b) (R1×R2)/(R1+R2) (c) R1 − R2 (d) √(R1×R2)
39. The Form Factor for a pure sine wave is approximately:
    (a) 0.707 (b) 1.0 (c) 1.11 (d) 1.414
40. RRB JE examinations apply negative marking of:
    (a) 1/4 mark (b) 1/3 mark (c) 1/2 mark (d) No negative marking
41. The Technical Abilities section in RRB JE CBT 2 typically carries how many marks?
    (a) 50 (b) 75 (c) 100 (d) 120
42. A synchronous generator (alternator) operates with:
    (a) Non-zero slip (b) Exactly zero slip, locked to supply frequency (c) No relationship to frequency (d) Variable frequency at constant speed
43. Which machine is most widely used as an AC industrial motor?
    (a) Synchronous motor (b) Induction motor (c) DC series motor (d) Stepper motor
44. A fuse operates by:
    (a) Sensing voltage drops only (b) Melting to interrupt the circuit above rated current (c) Automatically resetting (d) Increasing voltage during a fault
45. Earthing (grounding) primarily provides:
    (a) Increased voltage output (b) A safe path for fault currents and personnel safety (c) Reduced power factor (d) Increased transmission losses
46. A lower power factor generally results in:
    (a) Lower current draw for the same real power (b) Higher current draw and increased losses (c) No effect on losses (d) Automatically improved efficiency
47. A multimeter typically combines the functions of:
    (a) Ammeter, voltmeter, and ohmmeter (b) Only an ammeter (c) Only a wattmeter (d) Only a frequency meter
48. Traditional electromechanical energy meters use an induction-type mechanism with:
    (a) A rotating aluminium disc (b) A digital display only (c) A mercury column (d) A bimetallic strip
49. P-type semiconductors have an excess of majority charge carriers called:
    (a) Free electrons (b) Holes (c) Protons (d) Neutrons
50. Compared to open-loop systems, closed-loop systems generally provide:
    (a) Lower accuracy (b) Greater accuracy and disturbance rejection, at greater complexity (c) No difference in performance (d) Simpler construction with equal performance

Answer Key

1.(b)

2.(b)

3.(b)

4.(a)

5.(b)

6.(c)

7.(b)

8.(b)

9.(a)

10.(b)

11.(b)

12.(c)

13.(b)

14.(b)

15.(a)

16.(b)

17.(c)

18.(b)

19.(b)

20.(b)

21.(b)

22.(b)

23.(b)

24.(b)

25.(c)

26.(b)

27.(c)

28.(b)

29.(b)

30.(b)

31.(b)

32.(b)

33.(b)

34.(a)

35.(b)

36.(b)

37.(a)

38.(b)

39.(c)

40.(b)

41.(c)

42.(b)

43.(b)

44.(b)

45.(b)

46.(b)

47.(a)

48.(a)

49.(b) 50.(b)