← Junior Engineer
Past Questions
Second law of thermodynamics defines
A)
Enthalpy
B)
Entropy
C)
Internal energy
D)
Work
The second law of thermodynamics introduces the concept of entropy and states that the entropy of an isolated system never decreases. Enthalpy and internal energy are state functions, but they are not defined by the second law. Work is a mode of energy transfer, not the quantity defined by the second law.
Air supply in Diesel engines is usually
A)
10 percent deficient
B)
Stoichiometric
C)
About 40 percent surplus
D)
About 20 percent surplus
In a diesel engine, combustion is unthrottled and excess air is supplied to ensure complete burning of the injected fuel. Diesel engines generally operate with a much larger air-fuel ratio than stoichiometric, commonly with around 30–50% or more excess air. Hence, the usual air supply is about 40% surplus. Option (a) is wrong because diesel engines do not run air-deficient, and (b) is wrong because diesel engines do not use stoichiometric air supply in normal operation. Option (d) is too low compared with the usual excess air in diesel engines.
If the specific speed of a turbine is 800 the turbine should be
A)
Francis turbine
B)
Pelton turbine
C)
Kaplan turbine
D)
Fourneyron turbine
Specific speed indicates the type of turbine. Pelton turbines have low specific speed, Francis turbines have medium specific speed, and Kaplan turbines have high specific speed. A specific speed of about 800 falls in the high specific speed range, so the correct choice is Kaplan turbine. Fourneyron is an early form of reaction turbine and is not the standard classification used for this range.
The octane rating of petrol commercially available is usually
A)
90-100
B)
85-90
C)
75-80
D)
60-70
Commercial petrol generally has an octane rating in the range of about 85 to 90. Octane rating indicates the anti-knock quality of petrol; higher values mean better resistance to engine knocking. The other options are too low for regular commercial petrol: 75-80 and 60-70 are below usual petrol grades, while 90-100 is higher than what is usually available for standard commercial petrol.
In cooling towers the heat is dissipated mainly by
A)
Evaporation
B)
Radiation
C)
Conduction
D)
Convection
In a cooling tower, the warm water comes in contact with air and a small portion of the water evaporates. This evaporation removes latent heat from the remaining water, which is the main mechanism of heat dissipation. Radiation and conduction are negligible, while convection helps in heat transfer but is not the primary cooling process.
In a thermal power plant thermodynamic cycle used is
A)
Otto
B)
Carnot
C)
Brayton
D)
Rankine
A thermal power plant (steam power plant) works on the Rankine cycle, which uses water/steam as the working fluid. In this cycle, water is pumped to high pressure, heated in the boiler, expanded in the turbine, and then condensed back to water. Otto and Brayton cycles are used in IC engines and gas turbine plants respectively, while Carnot is only an ideal theoretical cycle.
A single unit of 50 MW is not generally available with which type of power plant?
A)
Nuclear power plant
B)
Gas turbine power plant
C)
Steam power plant
D)
Diesel engine power plant
A 50 MW single generating unit is generally not associated with a diesel engine power plant because diesel plants are usually used for small capacities due to high fuel cost, size limitations, and maintenance issues. In contrast, nuclear, gas turbine, and steam power plants commonly have units of 50 MW or more.
In MKS system, 1 atmospheric pressure is equal to
A)
1.0 kg/cm?
B)
1.033 kg/cm?
C)
1.10kg/cm?
D)
1.133kg/cm?
In the MKS system, 1 atmospheric pressure is approximately equal to 1.033 kgf/cm². This comes from the standard conversion of 1 atm = 1.01325 bar = 101325 N/m², which is about 1.033 kgf/cm². Hence option (b) is correct. The other options are not the standard equivalent values.
7, 15, 29, 59, 117, ?
A)
232
B)
233
C)
235
D)
236
The pattern is: multiply by 2 and subtract 1, then add 1 alternately.
7 × 2 + 1 = 15
15 × 2 - 1 = 29
29 × 2 + 1 = 59
59 × 2 - 1 = 117
So next: 117 × 2 + 1 = 235
Therefore, the correct answer is 235.
Which of the following engines can work on very lean mixture?
A)
Petrol engine
B)
Diesel engine
C)
Wankel engine
D)
Two stroke engine
A diesel engine can work on a very lean mixture because it takes in only air during the suction stroke and fuel is injected directly into the hot compressed air. This allows combustion even when the overall air-fuel ratio is much higher than stoichiometric. Petrol engines generally need a near-stoichiometric mixture, while Wankel and two-stroke engines are not specifically known for operating on very lean mixtures.
A Kaplan turbine is a
A)
high head mixed flow turbine
B)
low head axial flow turbine
C)
impulse turbine, inward flow
D)
reaction turbine, outward flow
A Kaplan turbine is a reaction turbine designed for low head and high discharge conditions. Its runner has propeller-type blades and the flow passes through the turbine axially, so it is classified as a low head axial flow turbine. Option (a) is incorrect because Kaplan is not a high-head mixed-flow turbine; that description is closer to Francis-type behavior. Option (c) is wrong because impulse inward-flow turbines are Pelton-type concepts, not Kaplan. Option (d) is wrong because Kaplan is not an outward-flow turbine.
Careful is to cautious as boastful is to
A)
humble
B)
arrogant
C)
joyful
D)
suspicious
The relationship is of near-synonyms. "Careful" and "cautious" have similar meanings. Similarly, "boastful" means showing excessive pride, which is closest to "arrogant." The other options do not match this synonym relationship: humble is the opposite of boastful, while joyful and suspicious are unrelated.
Which of the following is not a part of arc welding cost?
A)
Power consumption
B)
Cost of electrode
C)
Labor charges
D)
Soldering rods
In arc welding, the main cost components include power consumption, electrode cost, and labor charges. Soldering rods are used in soldering, not arc welding, so they are not part of arc welding cost.
Candid is to indirect as honest is to
A)
frank
B)
wicked
C)
untruthful
D)
truthful
‘Candid’ means frank or direct, so its opposite is ‘indirect’. Similarly, ‘honest’ means truthful, so its opposite is ‘untruthful’. Therefore the correct analogy is candid : indirect :: honest : untruthful.
Which part is not common between petrol and diesel engines?
A)
Air cleaner
B)
Battery
C)
Dynamo
D)
Fuel injector
A fuel injector is a component of a diesel engine, where fuel is injected directly into the combustion chamber at high pressure. Petrol engines generally use a carburetor or port fuel injection system, but in the traditional IC engine classification this part is not common to both petrol and diesel engines. Air cleaner, battery, and dynamo are common auxiliary components used in both types of engines.
Power assisted brakes are often provided on
A)
motor cycles
B)
air cooled engine vehicles
C)
road roller
D)
heavy duty vehicles
Power-assisted brakes are used where a large braking force is required with minimum driver effort. This is common in heavy duty vehicles such as trucks and buses. Motor cycles generally use simple mechanical/hydraulic brakes, and road rollers or air-cooled engine vehicles are not the standard application for power-assisted braking. Hence, the correct answer is heavy duty vehicles.
Embarrassed is to humiliated as frightened is to
A)
reckless
B)
agitated
C)
courageous
D)
terrified
The relationship is one of synonym/near-synonym. "Embarrassed" and "humiliated" both express a similar feeling of shame. Likewise, "frightened" and "terrified" both mean very afraid. The other options do not match this relationship: reckless = careless, agitated = disturbed, courageous = brave.
The units of dynamic viscosity velocity are
A)
Newton/m?.sec
B)
Newton-sec/m?
C)
kg-sec/m
D)
kg-m?/sec
Dynamic viscosity (μ) has SI unit of Pascal-second, which is equivalent to N·s/m^2. Using the relation between force and viscosity, μ = shear stress / velocity gradient, the unit becomes (N/m^2)/(1/s) = N·s/m^2. Therefore, the correct option is (b) Newton-sec/m^2. The other options do not match the standard SI unit of dynamic viscosity.
Motoring test on I.C. engines is conducted to measure
A)
Indicated horse power
B)
Brake horse power
C)
Pumping horse power
D)
Friction horse power
In a motoring test, the I.C. engine is driven by an external motor instead of producing power by combustion. The power required to rotate the engine at a given speed represents the losses due to friction and pumping, so the test is used to measure friction horsepower. Indicated horsepower is obtained from the indicator diagram, brake horsepower from a dynamometer, and pumping horsepower is not the main quantity measured by the motoring test.
Connecting rod is attached to the piston by the
A)
Rod cap
B)
Piston pin
C)
Cap roller bearing
D)
Cap bolt
The connecting rod is connected to the piston through the piston pin, also called the gudgeon pin or wrist pin. It allows the piston to oscillate while transmitting force to the connecting rod. The other options are parts associated with the connecting rod cap assembly or bearings, not the piston connection.
In a diesel engine, the temperature of gases under full load may be of the order of
A)
4N
B)
2N
C)
Half of N
D)
N
In a diesel engine, the temperature of gases under full load is typically of the order of about 1000 K, i.e., around N in such questions. The combustion in diesel engines occurs with excess air, but the peak gas temperature is still high due to compression ignition and rapid heat release. The other options (4N, 2N, Half of N) are not realistic for full-load diesel exhaust/combustion gas temperature in standard exam context.
Brake lining is mounted on
A)
Brake shoe
B)
Brake drum
C)
Wheel cylinder
D)
Master cylinder
Brake lining is the friction material fixed to the brake shoe in drum brakes. When the brake is applied, the lining rubs against the brake drum to produce braking action. The brake drum, wheel cylinder, and master cylinder do not carry the lining.
Which of the following is mounted between the engine and gear box?
A)
Clutch
B)
Differential gear
C)
Propeller shaft
D)
Reduction gear
The clutch is mounted between the engine and the gearbox so that engine power can be transmitted to or disconnected from the transmission as needed. The differential gear is placed in the axle assembly, the propeller shaft lies between the gearbox and rear axle in rear-wheel-drive vehicles, and reduction gear is not the component mounted between the engine and gearbox.
Which type of pump is different from other?
A)
Axial flow pump
B)
Plunger pump
C)
Mixed flow pump
D)
Multistage centrifugal pump
Axial flow pump, mixed flow pump, and multistage centrifugal pump are all types of rotodynamic pumps. A plunger pump is a positive displacement pump, so it is different from the others. Hence, the odd one out is Plunger pump.
Voltage across a _______ cannot change instantaneously.
A)
Resistor
B)
Inductor
C)
Capacitor
D)
Source
The voltage across a capacitor cannot change instantaneously because that would require an infinite current, since i = C(dv/dt). In practice, capacitor voltage changes continuously. By contrast, resistor voltage can change instantly with current, and inductor current cannot change instantaneously (not voltage).