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Current Affairs January 2024

What is the correct answer?

4

The thermal efficiency of diesel engines on weak mixtures is

A. Unaffected

B. Lower

C. Higher

D. Dependent on other factors

Correct Answer :

C. Higher


Related Questions

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4

The knocking in spark ignition engines can be reduced by

A. Retarding the spark

B. Increasing the engine speed

C. Both (A) and (B)

D. None of these

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4

The specific fuel consumption per BH hour for a petrol engine is approximately

A. 0.15 kg

B. 0.2 kg

C. 0.25 kg

D. 0.3 kg

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4

In the opposed piston diesel engine, the combustion chamber is located

A. Above the piston

B. Below the piston

C. Between the pistons

D. There is no such criterion

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4

In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.

A. Equal to

B. Below

C. Above

D. None of these

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4

A carburettor is used to supply

A. Petrol, air and lubricating oil

B. Air and diesel

C. Petrol and lubricating oil

D. Petrol and air

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4

The maximum propulsive efficiency of a turbojet engine is at a speed of

A. 1000 km/h

B. 2000 km/h

C. 2400 km/h

D. 3000 km/h

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4

Air fuel ratio at which a petrol engine cannot work is

A. 8 : 1

B. 10 : 1

C. 15 : 1

D. 20 : 1 and less

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4

The delay period in compression ignition engines depends upon

A. Temperature and pressure in the cylinder at the time of injection

B. Nature of the fuel mixture strength

C. Relative velocity between the fuel injection and air turbulence pressure of residual gases

D. All of the above

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4

The specific fuel consumption per BHP hour for diesel engine is approximately

A. 0.15 kg

B. 0.2 kg

C. 0.25 kg

D. 0.3 kg

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4

The thermodynamic cycle on which the petrol engine works, is

A. Otto cycle

B. Joule cycle

C. Rankine cycle

D. Stirling cycle

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4

Which of the following is false statement? Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following

A. Piston ring and cylinder wear

B. Formation of hard coating on piston skirts

C. Oil sludge in the engine crank case

D. Detonation

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4

In a four stroke cycle petrol engine, the compression

A. Starts at 40° after bottom dead centre and ends at 30° before top dead centre

B. Starts at 40° before bottom dead centre and ends at 30° after bottom dead centre

C. Starts at bottom dead centre and ends at top dead centre

D. May start and end anywhere

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4

The colour of exhaust from diesel engine is generally

A. White

B. Bluish

C. Black

D. Violet

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4

In a petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a

A. Fuel pump

B. Fuel injector

C. Spark plug

D. None of these

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4

The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be

A. Higher

B. Lower

C. Remain unaffected

D. None of the above

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4

By higher octane number of spark ignition fuel, it is meant that the fuel has

A. Higher heating value

B. Higher flash point

C. Lower volatility

D. Longer ignition delay

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4

The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed

A. 80°C

B. 120°C

C. 180°C

D. 240°C

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4

The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will

A. Increase

B. Decrease

C. Be independent

D. May increase or decrease depending on other factors

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4

In petrol engine, using a fixed octane rating fuel and fixed compression ratio, supercharging will _________ the knocking tendency.

A. Not effected

B. Decrease

C. Increase

D. None of these

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4

The ignition of the charge by some hot surface within the engine before the passage of spark is called

A. Pre-ignition

B. Detonation

C. Ignition delay

D. Auto-ignition

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4

The function of a distributor in a coil ignition system of I.C. engines is

A. To distribute spark

B. To distribute power

C. To distribute current

D. To time the spark

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4

The higher combustion chamber wall temperature in compression ignition engines will _________ knocking tendency.

A. Increase

B. Reduce

C. Not effect

D. None of these

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4

The following volume of air is required for consuming 1 litre of fuel by a four stroke engine

A. 1 m3

B. 5 m3

C. 56 m3

D. 910 m3

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4

In a four stroke cycle diesel engine, the inlet valve

A. Opens at 20° before top dead centre and closes at 40° after bottom dead centre

B. Opens at 20° after top dead centre and closes at 20° before bottom dead centre

C. Opens at top dead centre and closes at bottom dead centre

D. May open and close anywhere

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4

The thermal efficiency of a petrol engine is _________ as compared to diesel engine.

A. Same

B. Less

C. More

D. None of these

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4

In a four stroke cycle petrol engine, the inlet valve

A. Opens at top dead centre and closes at bottom dead centre

B. Opens at 20° before top dead centre and closes at 40° after bottom dead centre

C. Opens at 20° after top dead centre and closes at 20° before bottom dead centre

D. May open or close anywhere

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4

In order to eliminate knocking in compression ignition engines, there should be

A. Short delay period

B. Late auto-ignition

C. Low compression ratio

D. High self ignition temperature of fuel

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4

The brake power of a diesel engine, keeping other parameters constant, can be increased by

A. Decreasing the density of intake air

B. Increasing the temperature of intake air

C. Increasing the pressure of intake air

D. Decreasing the pressure of intake air

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4

Which of the following does not relate to a compression ignition engine?

A. Fuel pump

B. Fuel injector

C. Governor

D. Carburettor

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4

In a naturally aspirated diesel engine, the air is supplied by

A. A supercharger

B. A centrifugal blower

C. A vacuum chamber

D. An injection tube