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4

In a cycle, the spark lasts roughly for

A. 1 sec

B. 0.1 sec

C. 0.01 sec

D. 0.001 sec

Correct Answer :

D. 0.001 sec


Related Questions

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4

In compression ignition engines, swirl denotes a

A. Haphazard motion of the gases in the chamber

B. Rotary motion of the gases in the chamber

C. Radial motion of the gases in the chamber

D. None of the above

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4

The pressure at the end of compression in the case of diesel engine is of the order of

A. 6 kg/cm

B. 12 kg/cm

C. 20 kg/cm

D. 35 kg/cm

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4

It the temperature of intake air in IC engines is lowered, then its efficiency will

A. Increase

B. Decrease

C. Remain same

D. Increase up to certain limit and then decrease

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4

The two reference fuels used for cetane rating are

A. Cetane and iso-octane

B. Cetane and alpha-methyl naphthalene

C. Cetane and normal heptane

D. Cetane and tetra ethyl lead

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4

The pressure at the end of compression, in diesel engines, is approximately

A. 10 bar

B. 20 bar

C. 25 bar

D. 35 bar

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4

Which of the following statement is correct regarding petrol engines?

A. A fine fuel spray mixed with air is ignited by the heat of compression which is at a high pressure

B. The fuel supplied to the engine cylinder is mixed with necessary amount of air and the mixture in ignited with the help of a spark plug

C. The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition

D. All of the above

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4

The frictional power (F.P.) is given by

A. F.P. = B.P. - I.P.

B. F.P. = I.P. - B.P.

C. F.P. = B.P./I.P.

D. F.P. = I.P./B.P.

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4

The inlet value of a four stroke cycle I.C engine remains open for nearly

A. 180°

B. 125°

C. 235°

D. 200°

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4

A heat engine utilises the

A. Calorific value of oil

B. Low heat value of

C. High heat value of oil

D. Mean heat value of oil

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4

Thermal efficiency of a two stroke cycle engine is ________ a four stroke cycle engine.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

The ignition quality of petrol is expressed by

A. Cetane number

B. Octane number

C. Calorific value

D. All of these

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4

The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft

A. 1/2

B. 1

C. 2

D. 4

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4

In a four stroke cycle diesel engine, the exhaust valve

A. Opens at 30° before bottom dead centre and closes at 10° after top dead centre

B. Opens at 30° after bottom dead centre and closes at 10° before top dead centre

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

D. May open and close anywhere

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4

The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be

A. 25 %

B. 50 %

C. 70 %

D. 100 %

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4

In a coil ignition system of petrol engines, a condenser is connected across the contact breaker in order to

A. Prevent sparking across the gap between the points

B. Cause more rapid break of the primary current, giving a higher voltage in the secondary circuit

C. Both (A) and (B)

D. None of the above

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4

A fuel of cetane number 40 has the same ignition quality as a mixture of

A. 40% cetane and 60% alpha methyl naphthalene

B. 40% alpha methyl naphthalene and 60% cetane

C. 40% petrol and 60% diesel

D. 40% diesel and 60% petrol

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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 fuel in diesel engine is normally injected at pressure of

A. 5-10 kg/cm²

B. 20-25 kg/cm²

C. 60-80 kg/cm²

D. 90-130 kg/cm²

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4

The reason for supercharging in any engine is to

A. Increase efficiency

B. Increase power

C. Reduce weight and bulk for a given output

D. Effect fuel economy

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4

The increase in intake temperature of internal combustion engines will _________ efficiency.

A. Have no effect on

B. Increase

C. Decrease

D. None of these

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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

In the crankcase method of scavenging, the air pressure is produced by

A. Supercharger

B. Centrifugal pump

C. Natural aspirator

D. Movement of engine piston

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4

The compensating jet in a carburettor supplies almost constant amount of petrol at all speeds because the

A. Jet area is automatically varied depending on the suction

B. The flow from the main jet is diverted to the compensating jet with increase in speed

C. The diameter of the jet is constant and the discharge coefficient is invariant

D. Flow is produced due to the static head in the float chamber

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4

Which of the following statement is correct?

A. Compression ratio for petrol engines varies from 6 to 10

B. Higher compression ratio in diesel engines results in higher pressures

C. Petrol engines work on Otto cycle

D. All of the above

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4

Pick up the wrong statement

A. 2-stroke engine can run in any direction

B. In 4-stroke engine, a power stroke is obtained in 4-strokes

C. Thermal efficiency of 4-stroke engine is more due to positive scavenging

D. Petrol engines occupy more space than diesel engines for same power output

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4

The increase of efficiency of a compression ignition engine, as the load decreases, is due to

A. Higher maximum temperature

B. Qualitative governing

C. Quantitative governing

D. Hit and miss governing

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4

Number of working strokes per min. for a two stroke cycle engine is _________ the speed of the engine in r.p.m.

A. Equal to

B. One-half

C. Twice

D. Four-times

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4

The maximum temperature in the I.C. engine cylinder is of the order of

A. 500-1000°C

B. 1000-1500°C

C. 1500-2000°C

D. 2000-2500°C

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4

The injection pressure in a diesel engine is about

A. 10 bar

B. 100 bar

C. 150 bar

D. 500 bar

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4

If V₁ is the jet velocity and V₀ is the vehicle velocity, then propulsive efficiency of a turbojet engine is

A. V₁/(V₀ + V₁)

B. V₀/(V₀ + V₁)

C. 2V₀/(V₀ + V₁)

D. 2V₁/(V₀ + V₁)