The voltage required to produce a spark across the gap, between the sparking points is
2000 to 4000 volts
4000 to 6000 volts
6000 to 10,000 volts
10,000 to 12,000 volts
Correct Answer :
C. 6000 to 10,000 volts
Related Questions
In order to prevent knocking in spark ignition engines, the charge away from the spark plug should have
Low density
Low temperature
Long ignition delay
All of these
The cetane (C16H34) which is a straight chain paraffin, is assigned a cetane number of
0
50
100
120
In diesel engine, the compression ratio in comparison to expansion ratio is
Same
Less
More
Variable
In loop scavenging, the top of the piston is
Flat
Contoured
Slanted
Depressed
By higher octane number of spark ignition fuel, it is meant that the fuel has
Higher heating value
Higher flash point
Lower volatility
Longer ignition delay
A spark plug gap is kept from
0.3 to 0.7 mm
0.2 to 0.8 mm
0.4 to 0.9 mm
0.6 to 1.0 mm
In a diesel engine, the fuel is ignited by
Spark
Injected fuel
Heat resulting from compressing air that is supplied for combustion
Ignition
Diesel fuel, compared to petrol is
Less difficult to ignite
Just about the same difficult to ignite
More difficult to ignite
Highly ignitable
The knocking in spark ignition engines can be reduced by
Retarding the spark
Increasing the engine speed
Both (A) and (B)
None of these
Fuel consumption of diesel engines is not guaranteed at one quarter load because at such low loads
The friction is high
The friction is unpredictable
The small difference in cooling water temperature or in internal friction has a disproportionate effect
The engine is rarely operated
In a petrol engine, the mixture has the lowest pressure at the
Beginning of suction stroke
End of suction stroke
End of compression stroke
None of these
A supercharged engine as compared to an ordinary engine
Is lighter
Requires smaller foundations
Consumes less lubricating oil
All of these
Supercharging is essential in
Diesel engines
Gas turbines
Petrol engines
Aircraft engines
A fuel of cetane number 40 has the same ignition quality as a mixture of
40% cetane and 60% alpha methyl naphthalene
40% alpha methyl naphthalene and 60% cetane
40% petrol and 60% diesel
40% diesel and 60% petrol
The specific fuel consumption of a petrol engine compared to diesel engine of same H.P. is
Same
More
Less
Less or more depending on operating conditions
Theoretically, a four stroke cycle engine should develop _________ power as that of a two stroke cycle engine.
Half
Same
Double
Four times
The reason for supercharging in any engine is to
Increase efficiency
Increase power
Reduce weight and bulk for a given output
Effect fuel economy
The thermal efficiency of diesel engines is about
15 %
30 %
50 %
70 %
Air fuel ratio for idling speed of a petrol engine is approximately
1 : 1
5 : 1
10 : 1
15 : 1
A petrol engine, during suction stroke draws
Air only
Petrol only
A mixture of petrol and air
None of these
A diesel engine is _________ as compared to petrol engine, both running at rated load.
Equally efficient
Less efficient
More efficient
None of these
In a four stroke cycle petrol engine, the inlet valve
Opens at top dead centre and closes at bottom dead centre
Opens at 20° before top dead centre and closes at 40° after bottom dead centre
Opens at 20° after top dead centre and closes at 20° before bottom dead centre
May open or close anywhere
Detonation is harmful due to
Increase in the rate of heat transfer, there is a reduction in the power output and efficiency of the engine
Excessive turbulence which removes most of the insulating gas boundary layer from the cylinder walls
High intensity of knock causes crankshaft vibration and the engine runs rough
None of the above
The _________ engines can work on very lean mixture of fuel.
Spark ignition
Compression ignition
Both (A) and (B)
None of these
An hmh flame speed is obtained in diesel engine when air fuel ratio is
Uniform throughout the mixture
Chemically correct mixture
About 35% of rich mixture
About 10% of rich mixture
The output of a diesel engine can be increased without increasing the engine revolution or size in following way
Feeding more fuel
Heating incoming air
Scavenging
Supercharging
A stoichiometric air-fuel ratio is
Chemically correct mixture
Lean mixture
Rich mixture for idling
Rich mixture for over loads
The ratio of the brake power to the indicated power is called
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Volumetric efficiency
The voltage required to produce a spark across the gap, between the sparking points is
2000 to 4000 volts
4000 to 6000 volts
6000 to 10,000 volts
10,000 to 12,000 volts
The operation of forcing additional air under pressure into the engine cylinder is known as
Supercharging
Carburetion
Turbulence
Delay period