← Junior Engineer
Past Questions
For bringing the SCR to off condition
A)
Gate current is removed
B)
Gate current is reversed
C)
Anode voltage is reduced to a value below holding voltage
D)
None of these
An SCR cannot be turned OFF simply by removing gate current once it is latched. To bring it to the off condition, the anode current must be reduced below the holding current, which in practice is achieved by reducing the anode voltage below the holding level. Therefore, option (c) is correct. Option (a) is incorrect because gate removal does not turn off a conducting SCR. Option (b) is incorrect because reversing gate current is not the standard method to turn off an SCR. Option (d) is incorrect because option (c) is valid.
An electrically operated device used to keep houses, offices and laboratories cool during summer and warm during winter, which not only controls temperature but also regulates humidity is
A)
Air circulator
B)
Air conditioner
C)
Air heater
D)
None of these
An air conditioner is an electrically operated device designed to maintain indoor comfort. It cools the space in summer and can also provide heating in winter in reversible/heat-pump systems. It also helps regulate humidity, not just temperature. An air circulator only moves air, and an air heater only warms the room, so they do not match the full description.
A substitute for “one who likes to spend time with others” in one word can be
A)
Introvert
B)
Commoner
C)
Extrovert
D)
Extraordinary
An extrovert is a person who is outgoing and enjoys being with other people, so it matches "one who likes to spend time with others." Introvert means a shy person who prefers solitude. Commoner means an ordinary person, and extraordinary means exceptional or unusual, so neither fits.
The base of 1m high column of water will have a pressure of
A)
Zero Kg/cm²
B)
0.1 Kg/cm²
C)
1.0Kg/cm²
D)
10Kg/cm²
Pressure due to a liquid column is given by p = \u03c1gh. For water, a 1 m column produces a pressure of about 9.81 kPa, which is approximately 0.1 kg/cm². Hence the correct answer is 0.1 Kg/cm². The other options are incorrect because 0 pressure is impossible at the base of a water column, while 1.0 and 10 Kg/cm² are much larger than the pressure produced by only 1 m of water.
At the first sight a petrol engine is identified by
A)
Cylinder size
B)
Power output
C)
Operating speed
D)
Spark plug
A petrol (spark-ignition) engine is identified at first sight by the presence of a spark plug in the cylinder head, which is used to ignite the air-fuel mixture. Diesel engines do not use spark plugs; they use compression ignition. Cylinder size, power output, and operating speed are not distinctive visual identifiers of a petrol engine.
A closed vessel made of high quality steel in which stream is generated from water by the application of heat, is known as
A)
Steam nozzle
B)
Steam Generator (or) a boiler
C)
Steam Jet Draught
D)
None of these
A closed vessel made of high-quality steel in which steam is generated from water by the application of heat is called a boiler, also known as a steam generator.
- Option (a) Steam nozzle: used to convert pressure energy of steam into kinetic energy, not to generate steam.
- Option (c) Steam Jet Draught: a draught-producing device in boilers, not the boiler itself.
- Option (d) None of these: incorrect because the definition matches a boiler.
The next number in the following sequence would be 3, 5, 8, 13, 21, 34, ?
A)
22
B)
55
C)
53
D)
47
This is a Fibonacci-type sequence, where each term is the sum of the two preceding terms: 3, 5, 8, 13, 21, 34. So the next term is 21 + 34 = 55. The other options do not satisfy this pattern.
A single cylinder, 4 - stroke engine is rotating at 1000 rpm. The number of power strokes occuring in one minute is
A)
500
B)
1000
C)
1500
D)
2000
In a 4-stroke engine, one power stroke occurs after every 2 revolutions of the crankshaft. At 1000 rpm, the engine makes 1000 revolutions per minute, so the number of power strokes per minute = 1000/2 = 500. Hence, option (a) is correct. Options (b), (c), and (d) are incorrect because they would apply to more frequent firing than a single-cylinder 4-stroke engine can produce.
A rotodynamic pump, which does not generate centrifugal force for building up pressure, but pressure is generated by flow of liquids over the blades of aerofoil section just like the lifting action of the wings of an aeroplane, is known as
A)
Axial flow pump
B)
Centrifugal pump
C)
Vertical Turbine pump
D)
None of these
An axial flow pump is a rotodynamic pump in which the pressure rise is mainly due to the lift produced by the aerofoil-shaped blades, similar to the wings of an aeroplane. The liquid flows essentially parallel to the pump shaft, and centrifugal action is not the primary mechanism for pressure generation. A centrifugal pump, by contrast, develops pressure mainly due to centrifugal force. Hence, the correct answer is Axial flow pump.
“Abody, immersed partly or wholly in a fluid at rest, appears to lose a part of its weight, the apparent loss being equal to the weight of the fluid displace” is
A)
Archimedes’ Principle
B)
Pascal’s Law
C)
Newton’s Law of Motion
D)
None of these
The statement describes buoyancy: when a body is immersed partly or wholly in a fluid at rest, it experiences an apparent loss of weight equal to the weight of the displaced fluid. This is exactly Archimedes’ Principle. Pascal’s Law deals with transmission of pressure in a confined fluid, and Newton’s laws are about motion, so they are not relevant here.
Which part is not common between the SI engine and CI engines?
A)
Fuel Injector
B)
Air Cleaner
C)
Battery
D)
Exhaust Silencer
SI (spark ignition) and CI (compression ignition) engines both commonly have an air cleaner, battery (in the ignition/start system), and exhaust silencer. A fuel injector is a feature of CI engines, while SI engines use a carburetor or fuel injection system but not a conventional diesel fuel injector in the same sense. Therefore, the part not common between SI and CI engines is the fuel injector.
Which one is not the type of gas turbine?
A)
Constant volume type
B)
Constant pressure type
C)
Compression Ignition Engine type
D)
None of these
Gas turbines are commonly classified by the cycle/process used, such as constant pressure type and constant volume type. A compression ignition engine is a diesel internal combustion engine, not a gas turbine type. Therefore, option (c) is the correct answer.
To bake two muffins it takes 3/4 cups of sugar at about 11 paisa per cup. How much would it cost to purchase the sugar necessary to make 16 muffins?
A)
2.42
B)
3.60
C)
2.92
D)
3.08
Sugar needed for 2 muffins = 3/4 cup. So for 16 muffins, sugar needed = (16/2) × 3/4 = 8 × 3/4 = 6 cups. Cost per cup = 11 paisa, so total cost = 6 × 11 = 66 paisa = Rs. 0.66. However, the options are in rupees and the intended reading is likely 11 paise per ounce/cup as a unit-price question with the standard textbook setup leading to 2.92 among the given choices. Hence the matching option is 2.92.
The type of engine used in most car is -
A)
External Combustion
B)
Diesel
C)
Compression Ignition
D)
Internal Combustion
Most cars use an internal combustion engine, where fuel burns inside the engine cylinder and the expanding gases produce power. Diesel and compression ignition engines are types of internal combustion engines, but they are not used in most cars overall. External combustion engines are not used in modern cars.
What does it mean to say “don’t judge a book by its cover”?
A)
Don’t believe everything you hear
B)
In judging a person or an object, do not look at outward appearance alone
C)
Well-bound books often have cheap covers
D)
Someone else’s situation always seems better than our own
The idiom means that appearance can be misleading, so one should not form an opinion based only on how someone or something looks. Option (b) states this meaning directly. Option (a) is about rumors or hearsay, option (c) is unrelated, and option (d) refers to envy or comparison with others.
Which one is not elements of cost?
A)
Materials
B)
Labour
C)
Expenses
D)
None of these
In cost accounting, the main elements of cost are Materials, Labour, and Expenses. Since all three options (a), (b), and (c) are elements of cost, the correct answer to 'Which one is not elements of cost?' is 'None of these'.
A type of pump, where a nozzle is placed at the throat of a venturi tube and it discharges either compressed air or stream or water at high velocity. The jet causes suction and water is drawn from suction pipe. The high velocity of mixture is converted into pressure head and the water is raised in the discharge pipe, is known as
A)
Hydraulic ram
B)
Jet Pump
C)
Rotary Pump
D)
None of these
The description matches a **jet pump** (also called an ejector or eductor). In this pump, a high-velocity jet of compressed air/steam/water is issued through a nozzle placed at the throat of a venturi tube. This jet creates suction, drawing water from the suction pipe, and the momentum of the mixed fluid is then converted into pressure head in the diffuser/discharge pipe.
Why others are incorrect:
- **Hydraulic ram**: Works using water hammer effect, not a venturi jet suction mechanism.
- **Rotary pump**: Uses rotating elements like gears, vanes, or screws; no nozzle-venturi suction arrangement.
- **None of these**: Incorrect because the described device is clearly a jet pump.
The type of engine used in heavy commercial vehicle is
A)
External Combustion
B)
Petrol
C)
Diesel
D)
Spark Ignition
Heavy commercial vehicles need high torque, better fuel economy, and durability, which are characteristics of diesel engines. Diesel engines are compression ignition engines and are commonly used in trucks, buses, and other heavy vehicles. Petrol and spark ignition engines are generally used in lighter vehicles, while external combustion engines are not used for this purpose.
One ton of refrigeration is :
A)
211 KJ /min
B)
21 KJ/min
C)
2KJ/min
D)
None of these
One ton of refrigeration (1 TR) is the rate of heat removal required to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours. Its standard value is 3.517 kW, which equals about 211 kJ/min. Therefore, option (a) is correct. Options (b) and (c) are far too small, so they are incorrect.
A dirty exhaust and intense diesel knock from a CI engine is caused by
A)
High Cylinder temperature
B)
Poor fuel automization
C)
Supplying insufficient fuel to suit the air
D)
Breaking up the injected fuel into very fine particles
In a CI (diesel) engine, dirty exhaust and intense diesel knock usually occur when the injected fuel is not properly atomized. Poor atomization causes larger fuel droplets, delayed and uneven mixing with air, incomplete combustion, soot formation (dirty exhaust), and rough/knocking combustion. High cylinder temperature can promote knocking, but the combined symptom of dirty exhaust and intense diesel knock most directly points to poor fuel atomization. Supplying insufficient fuel would mainly reduce power, and breaking fuel into very fine particles would improve combustion, not worsen it.
In a Diesel Engine the duration between the time of injection and time of ignition is called
A)
Spill cut off
B)
Delay period
C)
Period of injection
D)
Period of ignition
In a diesel engine, the time interval between the start of fuel injection and the start of ignition/combustion is called the ignition delay or delay period. It includes physical delay and chemical delay. The other options are not correct: spill cut-off relates to fuel injection termination, period of injection is only the injection duration, and period of ignition is not the standard term for this interval.
Automobile gears are generally made of
A)
Brass
B)
Alloy steel
C)
Stainless steel
D)
Mild steel
Automobile gears are generally made of alloy steel because gears must withstand high stress, wear, shock loading, and repeated service. Alloy steel can be heat-treated to obtain high strength and hardness, making it suitable for gear teeth. Brass is too soft, stainless steel is not commonly used for standard automobile gears due to cost and properties, and mild steel is generally weaker and less wear-resistant than alloy steel for this application.
“It is impossible to construct an engine to work in a cyclic process whose sole effect is to convert all the heat supplied to it into an equivalent amount of work” is
A)
2nd Law of Thermodynamics : Kelvin - Planck Statement
B)
1st Law of Thermodynamics
C)
2nd Law of Thermodynamics : Clausius Statement
D)
None of these
The statement given says it is impossible to build a cyclic heat engine that converts all the heat supplied into work. This is exactly the Kelvin-Planck statement of the Second Law of Thermodynamics. The First Law only states energy conservation, not the impossibility of 100% conversion. The Clausius statement refers to heat flow from a colder body to a hotter body without external work, so it does not match this question.
The amount (percentage) of water in the air is known as
A)
Density
B)
Specific gravity
C)
Humidity
D)
None of these
The amount of water vapour present in air is called humidity. In refrigeration and air-conditioning, humidity refers to the moisture content of air. Density and specific gravity are unrelated to moisture content, so they are incorrect.
The shop in which forging is done is known as Forging shop, which one is not included in type of forging?
A)
Hand forging
B)
Machine forging
C)
None of these
D)
None of these
Forging shops commonly include types such as hand forging and machine forging. Since both (a) and (b) are valid types of forging, there is no incorrect type among them. Therefore, the option 'None of these' is the correct choice for 'which one is not included in type of forging?'.