MECHANIC MOTORVEHICLE

THEORY

SEMESTER – IV JULY 2018

The combustion in spark ignition engjne.is……..

a. Homogeneous        

b. Heterogeneous       

c. Laminar

d. None of these

Answer: a. Homogeneous        

The degree of turbulence increases…….…with the piston.speed.

a. Indirectly   

b. Directly     

c- Linearly

d  None of these

Answer: b. Directly     

Which one of the following is a CFC refrigerant?

a. R 744    

b. R290     

c. R 502

d. R718

Answer: c. R 502

Which motion of follower is best for high spee.d cams?

a. SHM follower motion

b. uniform acceleration and retardatior of foll0wer motion

c. Cycloidal motion follower

d. All of.these                                                                                                                                                        Answer: c. Cycloidal motion follower

The purpose of a choke on a carburetor is

a. To provide more air for the engine.

b. To increase the life of the engine

c. To make it run at higher rpm’s

d. To make it easier to crank a cold engine

Answer: d. To make it easier to crank a cold engine

In an electronic fuel injection, the servicing is

a. Difficult

b  EaSy

c. Very Easy                                                                                                                                   d. None of these                                                                                                                         Answer: a. Difficult

EF1 system can achieve

a. Proper injection timing

b. Proper injection quantity

c. Proper injection pressure                                                                                                             d. All of these                                                                                                                                Answer: d. All of these

Petrol or Gasoline is obtained from crude petroleum by means of

a. Distillation

b. Cracking     

c. Both (a) & (b)                                                                                                                                        d. None of these                                                                                                                          Answer: c. Both (a) & (b)

                                                                                                                                                                 Gasoline engines are …………..  than diesel engines.                                                                                                         a. Heavier                                                                                                                                               b. Lighter                                                                                                                            c. Unpredictable                                                                                                                                         d.  None of these                                                                                                                      Answer : b. Lighter

The function of a float chamber in a carburetor is to supply the fuel to the nozzle at a

a. Constant volume head

b. Constant pressure head

c. Variable pressure head                                                                                                                  d. None of these                                                                                                                             Answer : . Constant pressure head

The main metering system of the carburetor consists of

a. The fuel metering orifice through which fuel is drawn from the float chamber

b. The main discharge

c. The passage leading to the idling system

d. All of these

Answer : d. All of these

The functions of the main metering system are

a. To proportion the fuel-air mixture

b. To decrease the pressure at the discharge nozzle exit

c. To limit the air flow at full throttle

d. All of these

Answer : d. All of these

In an electronic fuel injection, the maintenance cost is

a. Low

b. High

c. Normal                                                                                                                                              d. None of these                                                                                                                         Answer : b. High

The main metering system of the carburetor controls the fuel feed for

a. Cruising

b. Full throttle operations

c.  Both(a)&(b)                                                                                                                                    d. None of these                                                                                                                            Answer : c.  Both(a)&(b)

In electronic fuel injection, there is improvement in the_efficiency due to

comparatively less resistance in the intake manifolds which will cause less pressure losses.

a. Mechanical

b. Volumetric

C. Overall

d. None of these.

Answer : b. Volumetric

Types of Multi-Point Fuel Injection system are

a. Port injection

b. Throttle body injection

c. Both(a)&(b)

d. None of these

Answer :c. Both(a)&(b)

In MPFI-Electronic Control System, the …………….. sensor sends information about the engine speed.

a. Speed

b. Ignition

c. Air-flow
d. Air-mass

Answer : b. Ignition

The following is not an injector fault

a. Nozzle wetness

b. Blue nozzle body

c. Excessive leak off                                                                                                                                  d. Blowholes                                                                                                                                        Answer : d. Blowholes

Commonly used refrigerant in commercial ice plant is

A  C02    

b. Freon 12

c. Ammonia                                                                                                                                                                   d. Air

Standardization of potentiometer is used for

a. Accuracy

b. Accuracy in measurement

c. Use of low voltage sources                                                                                                                       d. None of these                                                                                                                          Answer : c. Use of low voltage sources

The main aims of an engine management system is to achieve

a. High reliability and durability with lowest possible initial cost

b. High power output and torque

c. Low levels of gaseous and particulate emissions

d. All of these

Answer : d. All of these

A circuit breaker is

a. Power factor correcting device

b. A device to neutralize the effect of transients    

c. A waveform correcting device                                                                                                           d. A current interrupting device.                                                                                                            Answer : d. A current interrupting device.

23. The following is (are) the part(s) of Electronic Control Unit (ECU)

a. Injector control

b. Spark advance control

c. Idling control                                                                                                                                  d. All of these                                                                                                                                Answer : d. All of these

ECU is an electronic injection system used for

a. Calculating the appropriate injection timing

b. Meeting only certain operating conditions

c. Closing the injection valve only

d. None of these

Answer : a. Calculating the appropriate injection timing

Sensitivity of a sensor can be depicted by

a. Niquist plot

b. Pole- zero plot

c. Bode plot

d.  None of these

Answer : c. Bode plot

Change in output of sensor with change in input is

a. Threashold

b. Slew rate

c. Sensitivity                                                                                                                                    d. None of these                                                                                                                          Answer : c. Sensitivity

According to Faraday's law, EMF stands for

a. Electromagnetic field c.  Electromagnetic friction

b. Electromagnetic force d.  Electromotive force

c.  Electromagnetic friction                                                                                                                  d.  Electromotive force                                                                                                               Answer : d.  Electromotive force

For time varying currents, the field or waves will be

a. Electrostatic

b. Magneto static

c. Electromagnetic                                                                                                                d. Electrical                                                                                                                               Answer :

The following affect the voltage required to jump over the gap of spark plug

a. Shape of electrode forming gap

b. The conductivity of gases in the gap

c. Fuel-air mixture ratio existing in the gap

d. All of these

Answer : d. All of these

Following is (are) true for Hall Effect sensors.

a. They can operate as switches of high frequency

b. They cost less than electromechanical switches

c. They are free from contact bounce problem

d. All of these

Answer : d. All of these

During the charging of a lead-acid cell

a. Its voltage increases

b. It gives out energy

c. Its cathode becomes dark chocolate brown in colour

d. Specific gravity of H₂S0₄ decreases

Answer : a. Its voltage increases

The output voltage of a charger is

a. Less than the battery voltage

b. Higher than the battery voltage

c. The same as the battery voltage

d. None of these                                                                                                                        Answer : b. Higher than the battery voltage

The function of duct in air conditioning unit is:

a. Air cooling

b. Air cleaning

c. Air drying                                                                                                                                                       d.  distribution                                                                                                                            Answer : d.  distribution

When speed of an alternator is changed from 3600 r.p.m. to 1800 r.p.m., the generated e.m.f./phases will become
a. One-half

b. Twice

c. Four times                                                                                                                                  d. None of these                                                                                                                        Answer : a. One-half

Alternating current produced by alternator (AC generator) is converted to DC by
a. Stator

b. Brushes

c. Rectifier                                                                                                                                  d. Regulator                                                                                                                              Answer : c. Rectifier

Which starter does not provide high speed protection to the D.C. shunt motor?

a. Three point starter

b. Four point starter

c. Two point starter                                                                                                                               d. None of these                                                                                                                             Answer :

For the protection of D.C. series motor, which starter is commonly used?

a. Two point starter

b. Three point starter

c. Four point starter                                                                                                                       d. None of these                                                                                                                         Answer :

Radio interference from a fluorescent lamp can be reduced by

a. Putting two lamps in parallel

b. Eliminating choke

c. Putting a capacitor across the lamp                                                                                              d. None of these                                                                                                                              Answer : c. Putting a capacitor across the lamp

Which of the following is difficult to adopt for dimming?

a. GLS lamps

b. Cold cathode lamps

c. Fluorescent lamps                                                                                                                                   d. All of these                                                                                                                                     Answer : c. Fluorescent lamps

The mirror used for the head light of a car is

a. Spherical concave  

b Plane

c. Cylindrical

d. Parabolic Concave                                                                                                                 Answer : d. Parabolic Concave

Nitrogen is added with the argon in an incandescent lamp to

a. Reduce the temperature  

b. Reduce the possibility of arcing

c. Increase the brightness                                                                                                                         d. Increase the efficiency                                                                                                                Answer : b. Reduce the possibility of arcing

Latent heat is highest for

a. Refrigerant-22

b. Ammonia    

c. Water                                                                                                                                                   d. None of these                                                                                                                                       Answer : c. Water

Which is the hottest portion of the poppet valve during operation of S.I engine'

a. Valve face

b. Valve head

c. Valve stem                                                                                                                                            d. Valve neck                                                                                                                                   Answer : b. Valve head

Thermostatic expansion valve is used to maintain

a. Constant degree of superheat

b. Constant degree of sub-cooling

c Constant degree of super heat and sub-cooling                                                            d.None of these                                                                                                                      Answer : a. Constant degree of superheat

The thermostatic valves opens and provides passage for the flow of water towards the radiator at approximately

a. 90° C     

b. 150° C

c- 250°C

d. 300°C

Answer : a. 90° C     

Inductive proximity sensors can be effective only when the objects are of-materials.

a. Ferromagnetic

b. Diamagnetic

c. Paramagnetic                                                                                                                             d. All of these                                                                                                                                  Answer : a. Ferromagnetic

Global Positioning System (GPS) is a

a. Satellite Word Station

b. Satellite System

c. Satellite Signal                                                                                                                         d. Satellite Solution                                                                                                                 Answer : b. Satellite System

Smallest change which a sensor can detect is

a. Resolution

b. Accuracy

c Precision

d. Scale

Answer : a. Resolution

Choose wrong, size of image formed in a plane mirror

a. Could be taller than mirror

b. Height of image depends on object distance      

c. Width of image is same as of object                                                                                        d. Image height depends on object height                                                                                    Answer : a. Could be taller than mirror

Following type of sensors are used to generate information in object grasping and obstacle avoidance.

a. Hall Effect sensor

b. Proximity sensor

c. Light sensor                                                                                                                                     d.  OPtical sensors                                                                                                                     Answer : b. Proximity sensor