Railway-RRB ALP 2025 CBT 2 Electronics Mechanic Previous Year Question Paper and Answer Key Free PDF Download English Jul 28, 2026-Shift 1
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CBT Stage-2 | Electronics Mechanic | Question Paper with Answer Key
Test Date: 28/07/2026 | Test Time: 9:30 AM – 12:00 PM | Shift-1
Note: Correct Answer carries 1 mark. Incorrect Answer carries 1/3 Negative mark. Options marked with ✓ (bold) are correct as per official key.
PART-A (General / Common for all trades)
Questions 1 to 100
Q.1 Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements. Statements: Some glasses are spoons. All spoons are forks. Conclusions: (I) Some glasses are forks. (II) All forks are spoons.
A. Both conclusions (I) and (II) follow
B. Only conclusion (II) follows
C. Only conclusion (I) follows ✓
D. Neither conclusion (I) nor (II) follows
Correct Answer: C
Q.2 In this question, a group of numbers/symbols is coded using letter codes as per the codes given below and the conditions which follow. What will be the code for the following group? + 6 $ 2 7 (Codes table and conditions as given in original paper)
A. WSNYT
B. TSNWW
C. WRNYT ✓
D. STMWV
Correct Answer: C
Q.3 Which of the following statements correctly describes average velocity and its SI unit?
A. Average velocity is the total distance divided by total time, and its unit is kilometer per hour.
B. Average velocity is the total distance divided by total time, and its unit is meter per second.
C. Average velocity is the total displacement divided by total time, and its unit is meter per second. ✓
D. Average velocity is the total displacement divided by total time, and its unit is kilometer per hour.
Correct Answer: C
Q.4 A boat sails 40 km downstream and then 40 km upstream in a river. The boat's speed in still water is 12 km/hr and the speed of the stream is 4 km/hr. How much time does the boat take to cover the entire distance (both upstream and downstream)?
A. 8 hours
B. 7.5 hours ✓
C. 6 hours
D. 10 hours
Correct Answer: B
Q.5 Three pipes A, B and C can fill a tank in 12 hours, 18 hours and 24 hours, respectively. A leak at the bottom can empty the full tank in 36 hours. If all the pipes are opened together, in how many hours will the tank be filled? (Round off your answer to two decimal places.)
A. 9.45 hours
B. 5.56 hours
C. 3.33 hours
D. 6.55 hours ✓
Correct Answer: D
Q.6 What is the primary function of a fire hydrant in a workplace safety system?
A. Detecting smoke and warning employees
B. Removing hazardous fumes from the area
C. Activating fire alarms automatically in emergencies
D. Supplying large quantities of water to fight fires ✓
Correct Answer: D
Q.7 A diamond ring costs ₹85,000. Its price is reduced first by 11% and then by 4% on the reduced price. Find the final price of the ring after both discounts.
A. ₹72,604
B. ₹72,624 ✓
C. ₹74,624
D. ₹73,624
Correct Answer: B
Q.8 When a moving car suddenly applies brakes, its kinetic energy is transformed mainly into which form of energy?
A. Heat energy ✓
B. Sound energy
C. Potential energy
D. Light energy
Correct Answer: A
Q.9 Simplify: 60 - {(−8) × (−16 − 19 − 2)} ÷ [5 × {2 + (−1) × (−1)}]
A. 604/15 ✓
B. 594/15
C. 614/15
D. 608/15
Correct Answer: A
Q.10 Which statement best describes a 'point' in engineering drawing?
A. A point indicates a precise location but has no size, length, or width. ✓
B. A point is the intersection of two lines and always has measurable length.
C. A point is a short line segment used to mark measurements.
D. A point represents a small area with both length and width.
Correct Answer: A
Q.11 What is an email used for?
A. File storage
B. Creating documents
C. Sending messages ✓
D. Data processing
Correct Answer: C
Q.12 A, B, C, D, X, Y and Z are sitting around a circular table facing the centre of the table. Only two people sit between X and Z when counted from the right of X. Only two people sit between Z and D. Only three people sit between X and B. A sits to the immediate left of C. Who sits third to the left of Y?
A. Z
B. X
C. C ✓
D. A
Correct Answer: C
Q.13 An engineer is tasked with creating a hollow cone for a machine part, where the wall thickness must be consistent and the slant height is critical for assembly. Which factor is most important to ensure the cone will fit correctly in the final design?
A. Ensuring the slant height matches the assembly requirement ✓
B. Prioritizing uniform wall thickness over all other features
C. Matching only the overall height of the cone
D. Focusing only on base diameter for precise fit
Correct Answer: A
Q.14 The average of 8 numbers is 45. If one number, 59, is removed, what will the new average be?
A. 42
B. 43 ✓
C. 41.5
D. 42.5
Correct Answer: B
Q.15 In third angle projection, where is the object placed relative to the plane of projection?
A. The object is placed in the third quadrant ✓
B. The object is placed in the first quadrant
C. The object is placed in the second quadrant
D. The object is placed in the fourth quadrant
Correct Answer: A
Q.16 A train X crosses a man who is sitting in another train Y, which is moving in the opposite direction, in 8 seconds. However, when both trains are moving in the same direction, train X takes 20 seconds to pass the same man. If the length of train X is 360 meters and the length of train Y is 240 meters, what is the speed of train Y?
A. 45.8 km/h
B. 46.5 km/h
C. 45.3 km/h
D. 48.6 km/h ✓
Correct Answer: D
Q.17 An engineering student is tasked with creating a detailed side view of a complex machine part for an assembly drawing. Which approach will most accurately represent all features visible from the side while avoiding hidden overlaps or misinterpretations?
A. Sketch the side view freely without using projections from the main view
B. Use only hidden lines for representing features on the far side in the view
C. Project all visible elements from the side and omit hidden features unless needed ✓
D. Include all features even those not visible from the selected side view
Correct Answer: C
Q.18 What should come in place of the question mark (?) in the given series? 74, 83, 101, 128, ?, 209
A. 164 ✓
B. 176
C. 146
D. 155
Correct Answer: A
Q.19 E, F, G, H, L and M live on six different floors of the same building. The lowermost floor is numbered 1 ... Only three people live above G. Only two people live between L and E. Only two people live between M and G. E lives below G but above F. How many people live below H?
A. Three ✓
B. Four
C. One
D. Two
Correct Answer: A
Q.20 If 'A' stands for '+', 'B' stands for '×', 'C' stands for '÷' and 'D' stands for '−', what will come in place of the question mark (?) in the following equation? 14 A 30 B 45 C 15 D 9 = ?
A. 29
B. 27 ✓
C. 25
D. 28
Correct Answer: B
Q.21 A cyclist covers 120 meters in 16 seconds on a straight road, then immediately covers 180 meters in 24 seconds on a similar road segment. What is the average speed of the cyclist during the entire journey?
A. 8.0 meters per second
B. 7.0 meters per second
C. 6.5 meters per second
D. 7.5 meters per second ✓
Correct Answer: D
Q.22 An object has a mass of 10 kilograms. How does its weight on the Moon compare to its weight on Earth?
A. The object weighs zero on the Moon
B. The object weighs the same on both the Moon and Earth
C. The object weighs more on the Moon than on Earth
D. The object weighs less on the Moon than on Earth ✓
Correct Answer: D
Q.23 What is the main purpose of ambient air quality standards?
A. To ensure air is routinely sampled to map historical pollution trends.
B. To focus exclusively on industrial operations while ignoring other sectors.
C. To require all industries to reduce emissions by the exact same percentage.
D. To set legally permissible limits for specific pollutants to protect public health. ✓
Correct Answer: D
Q.24 Which approach most effectively reduces both nitrogen and phosphorus concentrations during wastewater treatment?
A. Biological and chemical nutrient removal ✓
B. UV disinfection following secondary treatment
C. Surface-flow constructed wetlands
D. Primary sedimentation with extended aeration
Correct Answer: A
Q.25 Which property of a fuse wire ensures it melts quickly when excess current flows?
A. High electrical resistance
B. Thick wire
C. High melting point
D. Low melting point ✓
Correct Answer: D
Q.26 When using a hand file during fitting operations, which action demonstrates adherence to tool safety protocols?
A. Fitting a proper handle securely to the tang ✓
B. Filing above shoulder height for better leverage
C. Holding the file near its tang during filing work
D. Applying excessive downward force when filing
Correct Answer: A
Q.27 O, P, Q, U and V have different heights. Only three people have heights between V and Q. P is taller than U but shorter than O. V is taller than Q. How many people are shorter than P?
A. Three
B. Two ✓
C. Four
D. One
Correct Answer: B
Q.28 A car travels on a highway, and its odometer records a reading of 180 km at 8:00 am and 240 km at 9:30 am. Based on this information, which statement best describes the car's average speed during this interval?
A. The car's average speed is 40 km per hour as calculated from the odometer readings and time interval. ✓
B. The car's average speed is 240 km per hour since that was the odometer reading at 9:30 am.
C. The car's average speed is 180 km per hour since that was the odometer reading at 8:00 am.
D. The car's average speed is 60 km per hour based only on the change in odometer readings.
Correct Answer: A
Q.29 Solve the system of equations: −3x + 2y − z = −1, 6x − 6y + 7z = −7, 3x − 4y + 4z = −6
A. x = −2, y = 2, z = 11
B. x = 1, y = 2, z = 2
C. x = 2, y = 2, z = −1 ✓
D. x = 2, y = 1, z = −3
Correct Answer: C
Q.30 Below are given two sets of numbers. In each set of numbers, certain mathematical operation(s) on the first number result(s) in the second number... Which of the given options follows the same set of operations as in the given sets? 10 − 100 − 50 − 25 ; 2 − 4 − 2 − 1
A. 12 − 144 − 62 − 31
B. 5 − 25 − 15 − 7
C. 4 − 16 − 8 − 4 ✓
D. 8 − 64 − 32 − 14
Correct Answer: C
Q.31 P, Q, R, S and T have different ages. T is elder than only one person. S is elder than P but younger than Q. R is elder than Q. Who is the youngest?
A. R
B. P ✓
C. Q
D. S
Correct Answer: B
Q.32 Statements: All girls are hens. No hen is a cat. Conclusion (I): No girl is a cat. Conclusion (II): Some cats are hens.
A. Only conclusion (I) follows ✓
B. Both conclusions (I) and (II) follow
C. Only conclusion (II) follows
D. Neither conclusion (I) nor (II) follows
Correct Answer: A
Q.33 If (x + 1/x) = 3, find the value of (x³ + 1/x³).
A. 18 ✓
B. 16
C. 15
D. 20
Correct Answer: A
Q.34 A mechanical engineer must design a flange joint where two pipes are to be connected at a 45-degree angle. Which method should the engineer use to accurately represent the intersection line on a technical drawing of the two cylindrical pipes?
A. Use only standard orthographic projection without auxiliary views
B. Draw a simple circle at the junction in the top view
C. Represent the intersection as a straight line in the side view
D. Draw the true shape of the intersection using auxiliary projection ✓
Correct Answer: D
Q.35 A father distributed two different amounts among his sons P, Q, R and S. First amount was distributed in the ratio 5 : 4 : 3 : 2 and the second amount was distributed in the ratio 6 : 7 : 8 : 9. If the second amount is thrice the first amount, then which son will get the maximum amount?
A. S ✓
B. Q
C. P
D. R
Correct Answer: A
Q.36 Based on the English alphabetical order, three of the following four letter-cluster pairs are alike in a certain way and thus form a group. Which letter-cluster pair DOES NOT belong to that group? (A) TN-ZD (B) WQ-CG (C) EY-KO (D) QK-VA
A. TN-ZD
B. WQ-CG
C. EY-KO
D. QK-VA ✓
Correct Answer: D
Q.37 Select the pair which follows the same pattern as that followed by the two pairs given below. Both pairs follow the same pattern. BIP : EMU GNU : JRZ
A. FMT : IQY ✓
B. XDE : PON
C. VCD : GRD
D. CGW : NHT
Correct Answer: A
Q.38 Refer to the following letter series and answer the question that follows. Counting to be done from left to right only. (Left) A T D E B R C L M Q O N P J M Q E A O Z W F U K S L (Right) How many such vowels are there, each of which is immediately preceded by a consonant and also immediately followed by a consonant?
A. 2
B. 0
C. 3 ✓
D. 1
Correct Answer: C
Q.39 If Rohan's income increases by 20% and his expenditure increases by 10%, then his savings increase by ₹1,200. If his original income was ₹12,000, what was his original expenditure? (Assume that savings = income − expenditure.)
A. ₹11,000
B. ₹9,000
C. ₹10,000
D. ₹12,000 ✓
Correct Answer: D
Q.40 In a certain code language, 'KING' is coded as '9713' and 'ITCH' is coded as '2945'. What is the code for 'I' in the given code language?
A. 9 ✓
B. 2
C. 4
D. 7
Correct Answer: A
Note: Questions 41 to 100 of Part-A follow the same pattern. Correct answers as per official key have been marked in the complete extraction. Full detailed options for all 100 questions are available in the source PDF. Key correct answers for remaining Part-A questions are compiled below for quick reference.
Quick Answer Key – Part A (Q.41 to Q.100)
41-C, 42-B, 43-D, 44-D, 45-C, 46-C, 47-C, 48-A, 49-D, 50-C, 51-D, 52-A, 53-A, 54-D, 55-A, 56-B, 57-B, 58-A, 59-C, 60-B, 61-B, 62-D, 63-C, 64-A, 65-C, 66-A, 67-C, 68-C, 69-B, 70-A, 71-C, 72-C, 73-C, 74-C, 75-B, 76-C, 77-B, 78-C, 79-D, 80-A, 81-D, 82-D, 83-B, 84-D, 85-A, 86-A, 87-B, 88-B, 89-D, 90-B, 91-D, 92-C, 93-A, 94-A, 95-C, 96-D, 97-D, 98-A, 99-B, 100-D
PART-B (Electronics Mechanic Trade Specific)
Questions 1 to 75
Q.1 Which safety action shall be completed first before replacing a blown fuse in an electrical circuit?
A. Replace the fuse with a copper wire
B. Replace the fuse with a higher current rating
C. Switch OFF the circuit supply ✓
D. Touch the fuse terminals to confirm the fault
Correct Answer: C
Q.2 How many pins are present on a standard PATA ribbon cable header for desktop hard drives?
A. 50 pins
B. 40 pins ✓
C. 68 pins
D. 34 pins
Correct Answer: B
Q.3 Which antenna is best suited for directional communication over long distances?
A. Monopole antenna
B. Dipole antenna
C. Isotropic antenna
D. Parabolic antenna ✓
Correct Answer: D
Q.4 Which electrical quantity is defined as the potential difference between two points in an electrical circuit?
A. Voltage ✓
B. Power
C. Resistance
D. Current
Correct Answer: A
Q.5 You measure an intact SMD diode in the high-frequency switching stage of an LED driver. The multimeter forward voltage drop reads 0.240 V. What specific type of diode does this low voltage threshold identify?
A. Zener Diode
B. Light Emitting Diode (LED)
C. Standard Silicon Rectifier Diode
D. Schottky Diode ✓
Correct Answer: D
Q.6 A technician connects a load to the output of a half-wave rectifier without using a filter. What is the nature of the voltage across the load?
A. Pure DC voltage
B. Alternating voltage
C. Pulsating DC voltage ✓
D. Pulsating AC voltage
Correct Answer: C
Q.7 If the equivalent inductance in a Hartley oscillator is doubled, the frequency is:
A. Increased by √2
B. Halved
C. Reduced by √2 ✓
D. Doubled
Correct Answer: C
Q.8 When a zero crossing detector is used to measure the frequency of a periodic AC signal, what quantity must be counted?
A. The phase difference between input and output signals
B. The average voltage level of the output signal
C. The number of input voltage peaks per cycle
D. The number of output transitions per unit time ✓
Correct Answer: D
Q.9 How does Hard Disk store data in a desktop computer?
A. Paper tape
B. Magnetic platters ✓
C. Optical discs
D. Flash chips only
Correct Answer: B
Q.10 The working principle of a crystal oscillator is based on:
A. Piezoelectric effect ✓
B. Hall effect
C. Thermionic emission
D. Photoelectric effect
Correct Answer: A
Q.11 During a laboratory test, a trainee builds an RS flip-flop using NOR gates (active-HIGH inputs). Initially, the output Q = 0. The trainee applies S = 1 (Set input) and R = 0 (Reset input). After this, both inputs are returned to S = 0 and R = 0. What will happen to the output Q?
A. Q will continuously toggle between 0 and 1.
B. Q will return to 0 after inputs become 0.
C. Q will remain at 1 after inputs become 0, holding the last state. ✓
D. Q will become invalid when inputs return to 0.
Correct Answer: C
Q.12 Which set of terminals is commonly used to connect a Field Effect Transistor in a circuit?
A. Emitter, Collector, Base
B. Positive, Negative, Neutral
C. Anode, Cathode, Grid
D. Gate, Drain, Source ✓
Correct Answer: D
Q.13 Why are optical fibers less susceptible to electromagnetic interference compared to copper wires?
A. They are thicker than copper wires
B. They are covered with metal
C. They have higher resistance
D. They use light instead of electrical signals ✓
Correct Answer: D
Q.14 During the operation of a two-phase stepper motor, one of its phase windings becomes disconnected. What is the most likely effect on the performance of the motor?
A. The motor will continue to operate normally with full torque.
B. The motor will experience a significant reduction in torque and may fail to step accurately. ✓
C. The motor efficiency will improve due to reduced power consumption.
D. The motor will rotate at twice its rated speed.
Correct Answer: B
Q.15 Which trigonometric ratio represents the opposite side divided by the hypotenuse in a right triangle?
A. Tangent
B. Sine ✓
C. Cotangent
D. Cosine
Correct Answer: B
Q.16 Which component provides power to the motherboard and other devices?
A. RAM
B. Heat Sink
C. SMPS ✓
D. HDD
Correct Answer: C
Q.17 Two resistors of 8 Ω and 24 Ω are connected in parallel across a 12 V supply. What is the total current drawn from the source?
A. 1 A
B. 0.5 A
C. 2 A ✓
D. 4 A
Correct Answer: C
Q.18 Which feature best distinguishes a stud extractor from an open-end spanner in its intended application?
A. A stud extractor requires external heating before use, while an open-end spanner does not.
B. A stud extractor is longer than an open-end spanner, providing greater torque.
C. A stud extractor grips and removes a stud, while an open-end spanner fits the flats of a bolt. ✓
D. A stud extractor is used only for tightening, while an open-end spanner is used only for loosening.
Correct Answer: C
Q.19 A semiconductor sample shows conduction mainly due to holes, while electrons exist only in small numbers due to thermal generation. Identify the semiconductor type.
A. N-type semiconductor at room temperature
B. Intrinsic semiconductor at room temperature
C. P-type semiconductor at room temperature ✓
D. Intrinsic semiconductor at 0 K
Correct Answer: C
Q.20 Which internal hardware component of an LCD TV is responsible for regulating, filtering, and distributing the appropriate low-voltage direct current (DC) operational power rails required by the main logic board and the panel timing controller?
A. T-CON microprocessing chip
B. Liquid Crystal Display (LCD) shutter matrix
C. Low-Voltage Differential Signaling (LVDS) interface
D. Switch-Mode Power Supply (SMPS) board ✓
Correct Answer: D
Q.21 While free-hand sketching a circular pipe from a very steep viewing angle, the circular end appears as a narrow ellipse. Which statement is correct?
A. Both axes reduce equally, forming a smaller circle
B. The major axis becomes twice the true diameter, while the minor axis remains unchanged
C. The major axis equals the true diameter, while the minor axis becomes very small ✓
D. The minor axis equals the true diameter, while the major axis becomes very small
Correct Answer: C
Q.22 Which factor determines the selection of a soldering iron tip for a solder joint?
A. The storage condition of the soldering iron
B. The size and type of the solder joint ✓
C. The frequency of tip cleaning
D. The color of the soldering iron handle
Correct Answer: B
Q.23 A technician connecting a desktop PC to a network switch in a modern office environment should use a ______ cable terminated with ______ connectors to establish a stable local connection.
A. twisted pair; RJ45 ✓
B. fiber optic; SC
C. USB; Type A
D. coaxial; BNC
Correct Answer: A
Q.24 During a lab experiment, the current through a magnetizing coil is increased, while the magnetic path length remains unchanged. What will happen to the magnetic field strength?
A. It becomes zero
B. It decreases
C. It increases ✓
D. It remains constant
Correct Answer: C
Q.25 In an n-channel enhancement mode MOSFET, what must be applied to the gate terminal relative to the source to turn the device on?
A. A zero voltage
B. A negative voltage
C. A gate current
D. A positive voltage ✓
Correct Answer: D
Q.26 In engineering drawing practice, which lettering convention is preferred for marking part numbers to maintain clarity, readability, and uniformity?
A. Use lowercase letters for small-sized part numbers to save space
B. Use a mixture of uppercase and lowercase letters for all part numbers
C. Use lowercase letters for part numbers to reduce writing effort
D. Use uppercase letters for all part numbers to maintain standardization ✓
Correct Answer: D
Q.27 In a Pulse Width Modulation (PWM) signal, the duty cycle is defined as:
A. Variation in the amplitude of the pulses
B. Variation in the frequency of the pulses
C. Phase difference between input and output signals
D. Ratio of the pulse ON-time (width) to the total time period of the signal ✓
Correct Answer: D
Q.28 What is the first safety step before dismantling a desktop computer?
A. Switch off and unplug the power supply ✓
B. Remove RAM from all RAM slots
C. Open the cabinet
D. Disconnect data cables
Correct Answer: A
Q.29 Which of the following statements about HDDs is correct in computer hardware technology?
A. HDDs store data on spinning magnetic disks ✓
B. HDDs use flash memory to store data
C. HDDs are used for temporary storage only
D. HDDs use optical discs for storage
Correct Answer: A
Q.30 Which of the following is a type of RC Oscillator?
A. Hartley Oscillator
B. Crystal Oscillator
C. Colpitts Oscillator
D. Phase Shift Oscillator ✓
Correct Answer: D
Q.31 What happens if an amplifier is not properly biased?
A. It always turns off the amplifier
B. It improves efficiency
C. It increases output power
D. It may cause distortion ✓
Correct Answer: D
Q.32 During circuit testing across a PN junction diode, a technician finds that holes are responsible for electrical conduction in a semiconductor. Which region of a PN junction diode does this indicate?
A. Depletion region
B. Intrinsic region
C. N-type region
D. P-type region ✓
Correct Answer: D
Q.33 In a JK flip flop, the J input mainly performs which function when K = 0 and the clock is active?
A. The Set input ✓
B. The Reset input
C. The Clock input
D. The Toggle input
Correct Answer: A
Q.34 How should screws be tightened when mounting a Hard Disk Drive (HDD) in a desktop computer?
A. Tighten only one side
B. Leave screws slightly loose for HDD to move freely
C. Tighten screws evenly and firmly without over-tightening ✓
D. Tighten as much as possible with full force
Correct Answer: C
Q.35 What is the configuration called when the emitter terminal of a transistor is common to both input and output circuits?
A. Common base
B. Emitter follower
C. Common collector
D. Common emitter ✓
Correct Answer: D
Q.36 An industrial engineer wants to optimize a photoelectric switch system for detecting various packages on a conveyor belt... Which of the following changes would most improve the switch's detection reliability for all package types?
A. Using a heavier sensor for mounting stability
B. Increasing supply voltage to the sensor within rated limits
C. Adjusting the sensor's sensitivity and alignment to account for target surface characteristics ✓
D. Changing wire insulation material for better signal integrity
Correct Answer: C
Q.37 In the two-wattmeter method used for measuring power in a balanced three-phase load, both wattmeters show equal readings. Based on this observation, what is the power factor of the load?
A. 0
B. 1.0 ✓
C. 0.5
D. 0.866
Correct Answer: B
Q.38 To connect a local computer to a network switch, a technician must crimp an 8-pin connector onto the Ethernet cable and plug it directly into the switch's matching ________.
A. RJ45; LAN port ✓
B. USB; console interface
C. BNC; coaxial socket
D. RJ11; telephone jack
Correct Answer: A
Q.39 How does a voltage cut-off system contribute to the reliability of a power inverter in industrial use?
A. It ensures the inverter operates only within safe voltage parameters. ✓
B. It increases the battery life in all circumstances.
C. It maintains efficiency regardless of input voltage.
D. It directly lowers electromagnetic interference.
Correct Answer: A
Q.40 A Pulse Amplitude Modulation signal can be recovered at the receiver end using a/an ________.
A. Attenuator
B. Inverter
C. Low-pass filter ✓
D. High-pass filter
Correct Answer: C
Q.41 In an operational amplifier integrator circuit, which component acts as feedback between the output and the input?
A. Transistor
B. Capacitor ✓
C. Resistor
D. Inductor
Correct Answer: B
Q.42 Which connection interface should be used to link a high-definition (HD) digital set-top box to a modern LED or LCD TV to transmit both uncompressed digital video and multi-channel audio through a single cable while supporting Consumer Electronics Control (CEC)?
A. Composite Video (RCA)
B. Component Video (YPbPr)
C. HDMI ✓
D. S-Video
Correct Answer: C
Q.43 Which operational amplifier configuration is commonly used in zero crossing detectors?
A. Non-inverting amplifier with positive feedback is used.
B. Inverting amplifier with negative feedback is used.
C. Integrator circuit with resistive feedback is used.
D. Comparator configuration without feedback is used. ✓
Correct Answer: D
Q.44 In a three-phase, four-wire electrical distribution system, the fourth pole of a four-pole Miniature Circuit Breaker (MCB) is generally used for switching and protecting which conductor?
A. Earth conductor
B. Control circuit conductor
C. Neutral conductor ✓
D. Pilot wire
Correct Answer: C
Q.45 Which motherboard component is used to connect storage devices like HDD or SSD in desktop computer system?
A. SATA port ✓
B. RAM slot
C. USB port
D. PCIe slot
Correct Answer: A
Q.46 What is the resistance value of a surface-mount resistor marked '472' according to SMD resistor code conventions?
A. 470 ohms
B. 4700 ohms ✓
C. 4.7 ohms
D. 47000 ohms
Correct Answer: B
Q.47 A work area contains flammable chemicals and moving machinery. Which combination of safety signs is most appropriate for these hazards?
A. Caution signs for chemicals and warning signs for exits
B. Danger signs for machinery and caution signs for chemicals
C. Warning signs for chemicals and caution signs for machinery
D. Danger signs for chemicals and warning signs for machinery ✓
Correct Answer: D
Q.48 What is the main function of the sensors in an IoT system?
A. To store large amounts of information
B. To collect data from the environment ✓
C. To process collected data
D. To perform an action that changes the environment
Correct Answer: B
Q.49 In a single-phase fan or motor circuit used in workshop practice, why is a capacitor connected in series with the auxiliary winding?
A. To increase conductor resistance permanently
B. To produce phase difference for better starting torque ✓
C. To act as a fuse during overload
D. To reduce the supply frequency
Correct Answer: B
Q.50 How does the construction of a MOSFET help to achieve high input impedance?
A. The gate is insulated from the channel by a thin oxide layer ✓
B. The gate uses a resistive layer to limit current
C. The gate is connected directly to the channel
D. The device has a thick substrate for support
Correct Answer: A
Q.51 What does 'hand off' mean in the context of cell phones?
A. Make a new phone call
B. Charge the phone battery
C. Turn off the cell phone
D. Handover a call from one cell to another ✓
Correct Answer: D
Q.52 What is the function of an HDMI port when connecting an external source device to an LED or LCD TV?
A. To step down the main AC power voltage to safely operate the internal TV logic boards
B. To convert incoming analog video signals into digital formats inside the TV panel
C. To transmit uncompressed digital video and multi-channel audio simultaneously through a single cable ✓
D. To automatically increase the native optical refresh rate of the liquid crystal display pixels
Correct Answer: C
Q.53 What is the output Y of the following digital circuit if the input A = 1? (Note: Both the logic gates shown in the diagram are NOT gates.)
A. 0
B. High Impedance State
C. Undefined
D. 1 ✓
Correct Answer: D
Q.54 In a Common-Base (CB) transistor amplifier, the phase difference between the input voltage (emitter-base) and the output voltage (collector-base) is:
A. 180°
B. 90°
C. 0° ✓
D. 45°
Correct Answer: C
Q.55 If the input resistor of an inverting amplifier using OP-AMP is doubled and the feedback resistor remains the same, what happens to the magnitude of voltage gain?
A. It is halved ✓
B. It doubles
C. Stays the same
D. Becomes one fourth
Correct Answer: A
Q.56 Which of the following components are used to determine the frequency of oscillation in a Colpitts oscillator?
A. Diodes and resistors
B. Capacitors and inductor ✓
C. Resistors and capacitors
D. Inductor and resistors
Correct Answer: B
Q.57 A wire of some material has resistance 10 ohm at a certain length. To make its resistance 5 ohm using the same material and same cross-sectional area, what should be the new length?
A. Half of the original length ✓
B. Double the original length
C. Same as the original length
D. One fourth of the original length
Correct Answer: A
Q.58 Which of the following is NOT a sensor performance characteristic?
A. Range
B. Cost ✓
C. Sensitivity
D. Linearity
Correct Answer: B
Q.59 What is the phase shift required in RC phase shift oscillator from the entire feedback RC network to produce oscillations?
A. 90 degrees
B. 180 degrees ✓
C. 360 degrees
D. 270 degrees
Correct Answer: B
Q.60 When following the proper procedure to read voltage using a PMMC Voltmeter, which type of voltage can be measured accurately?
A. Alternating current (AC) voltage only
B. Both AC and DC voltage accurately
C. Direct current (DC) voltage only ✓
D. High-frequency AC voltage only
Correct Answer: C
Q.61 What problem can occur with a Digital Storage Oscilloscope (DSO) if its sampling rate is too low for a high-frequency signal, compared to an analog CRO?
A. The entire display screen will permanently turn off due to over-sampling.
B. The input signal will automatically switch to a direct current measurement mode.
C. The analog input probe tips will melt due to excessive heat generation.
D. Aliasing error, where the displayed waveform appears as an incorrect low-frequency signal shape. ✓
Correct Answer: D
Q.62 Which component is used to set biasing in a transistor amplifier but, if omitted, leads to unstable operation?
A. Transformer
B. Inductor
C. Resistor network ✓
D. Diode
Correct Answer: C
Q.63 Which phase relationship exists between input and output signals in a Common Emitter amplifier?
A. Output is in phase with input
B. 180° phase shift ✓
C. Output leads input by 90°
D. Output lags input by 90°
Correct Answer: B
Q.64 A standard multiplexed 6 by 4 LED matrix contains a total of ______ independent light-emitting nodes, which can be fully operated using a minimum of ______ microcontroller control pins.
A. 24; 24
B. 10; 24
C. 48; 48
D. 24; 10 ✓
Correct Answer: D
Q.65 Which of the following is a primary criterion when choosing a sensor for monitoring temperature in a manufacturing process?
A. Color of the sensor housing
B. Overall cost of the sensor
C. Accuracy of the sensor readings ✓
D. Physical size of the sensor
Correct Answer: C
Q.66 A 1 kHz square wave signal is applied to the input A of a NOT gate. What will be observed at the output of the NOT gate?
A. A 1 kHz square wave signal identical to the input
B. A 1 kHz square wave signal inverted (complemented) with respect to the input ✓
C. A constant LOW (0) signal
D. A constant HIGH (1) signal
Correct Answer: B
Q.67 In an 8051 microcontroller, during a debugging session, several PUSH instructions are executed, and the stack pointer reaches address 31H. Which memory area is now being used for stack storage?
A. Register bank area
B. Program memory area
C. Bit-addressable RAM area
D. General-purpose RAM area ✓
Correct Answer: D
Q.68 While diagnosing an NPN BJT in a SOT-23 package, your multimeter positive probe (+) is locked on the Base (Pin 1). Measuring to Pin 3 reads 0.6 V, while measuring to Pin 2 reads 0.68 V. Which pin is the Emitter?
A. Neither pin; the transistor is broken because the readings don't match.
B. Pin 2 is the Emitter, because it has the higher voltage drop. ✓
C. Both pins are identical and can be used interchangeably.
D. Pin 3 is the Emitter, because it has the lower voltage drop.
Correct Answer: B
Q.69 A technician notices the relay in a stabilizer frequently clicks on and off rapidly when connected to an SMPS. What is the most probable issue?
A. The relay is stuck in one position
B. The input voltage is fluctuating rapidly ✓
C. The stabilizer has a blown fuse
D. The SMPS is overloaded
Correct Answer: B
Q.70 While designing a system using an 8051 microcontroller, the lower address byte and data are multiplexed on the same lines. Which hardware component is required to hold the lower address byte temporarily for correct memory access?
A. Encoder
B. Multiplexer
C. Subtractor
D. Latch ✓
Correct Answer: D
Q.71 A telecommunications company observes call drops at the borders of adjacent cell sites. Which cell site configuration adjustment would minimize this issue?
A. Assigning the same frequency to neighboring cell sites
B. Decreasing the height of all cell site antennas
C. Reducing the transmission power of each cell site
D. Introducing overlapping coverage areas with handover protocols ✓
Correct Answer: D
Q.72 Three identical 12 V batteries are connected in parallel to supply a load current of 18 A. Assuming equal sharing, how much current is supplied by each battery?
A. 9 A
B. 4 A
C. 6 A ✓
D. 18 A
Correct Answer: C
Q.73 Which statement correctly distinguishes a primary battery from a secondary battery?
A. A primary battery is generally non-rechargeable, while a secondary battery can be recharged and reused ✓
B. A primary battery is used only in automobiles, while a secondary battery is used only in torches
C. A primary battery always has higher voltage than a secondary battery
D. A primary battery can be recharged many times, while a secondary battery cannot be recharged
Correct Answer: A
Q.74 A draftsman needs to construct a precise 75° angle without using a protractor. Which combination of instruments should be used?
A. Use two 45° set-squares together against a T-square
B. Use a divider to bisect a 120° angle accurately
C. Use a mini-drafter aligned with a T-square edge
D. Use a 45° set-square with a 30°-60° set-square against a T-square ✓
Correct Answer: D
Q.75 An n-type semiconductor is formed by doping with:
A. Pentavalent impurities ✓
B. Divalent impurities
C. Monovalent impurities
D. Trivalent impurities
Correct Answer: A
— End of Question Paper with Answer Key —
Prepared for study purpose from official RRB ALP Stage-2 CBT-2 Electronics Mechanic (28 July 2026, Shift-1) paper.
Correct answers marked with ✓ as per the provided answer key.
RRB ALP 2025 CBT 2 Electronics Mechanic Question Paper and Answer Key PDF English (Jul 28, 2026) (Shift 1)
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