This set of Automobile Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Measurements and Testing”.
1. To which of the following Morse test is applicable?
a) Single-cylinder SI engines
b) Single-cylinder CI engines
c) Multi-cylinder CI engines
d) Single and multi-cylinder SI and CI engines
View Answer
Explanation: The Morse test is used to measure the indicated power (IP) from multi-cylinder CI engines. The test consists of obtaining the indicated power (IP) of the CI engines without any apparatus.
2. For which of the following the Chemiluminescence analyzer is used to measure?
a) NOx
b) CO
c) HC
d) CO2
View Answer
Explanation: The Chemiluminescence analyzer is used to measure NOx in the exhaust gases from the engine. The principle of measurement is based on Chemiluminescence reaction between ozone and NO. It results in the formation of excited NO2.
3. Which of the following is the best method to measure the speed?
a) Mechanical tachometer
b) Electrical tachometer
c) Magnetic pickup
d) Mechanical counters
View Answer
Explanation: Magnetic pickup is the best device to measure the speed. Mechanical and electrical tachometers are affected by temperature variation and those are not accurate.
4. Which of the following is the most accurate method of determining friction power?
a) Morse test
b) Willian’s line
c) Motoring test
d) Measurement of brake and indicated power
View Answer
Explanation: The friction power can be obtained by measurement of the brake and indicated power. The indicated power can be obtained by indicated diagram and brake power obtained by a dynamometer.
5. What is the requirement of the air box in the airbox method of measuring airflow?
a) To dump out the pulsation
b) To provide the constant velocity of flow
c) To have a constant flow
d) To have a constant temperature
View Answer
Explanation: The airbox is used to dump out the pulsation while measuring the airflow. In IC engines, the satisfactory measurement of the air consumption is difficult because the flow is pulsating due to the cyclic nature of the engine and because the air is a compressible fluid.
6. For which of the following the flame ionization detector (FID) is used to measure?
a) CO
b) HC
c) CO2
d) NOx
View Answer
Explanation: Flame ionization detector (FID) is used to measure the hydrocarbon concentration. Ionization is the characteristic of HC compound.
7. Which of the following is the most accurate dynamometer?
a) Eddy current dynamometer
b) Prony brake dynamometer
c) Hydraulic type dynamometer
d) Swinging field type dynamometer
View Answer
Explanation: Swinging field type dynamometer is the most accurate dynamometer. It consists of an electrical machine which may be run either by motor or generator.
8. For which of the following the non-dispersive infra-red (NDIR) analyzer is used to measure?
a) CO2
b) CO
c) HC
d) NOx
View Answer
Explanation: Non-dispersive infra-red (NDIR) analyzer is used to measure CO. The method of detection is based on the principle of selective absorption of the infrared energy of particular wavelength unique to a certain gas which will be absorbed by that gas.
9. What can be obtained from the engine indicator diagram?
a) Indicated mean effective pressure
b) Brake mean effective pressure
c) Relative efficiency
d) Mechanical efficiency
View Answer
Explanation: The engine indicator diagram is used to obtain the indicated mean effective pressure. Pressure-volume, P-V, and pressure-crank angle, P-θ is the two types of indicator diagram that can be obtained from an engine. Both these indicator diagrams are mutually convertible.
10. On which of the following does brake mean effective pressure (BMEP) in an engine depend upon?
a) Speed and torque
b) Speed and power
c) Torque
d) Speed
View Answer
Explanation: Brake power = 2πNT / 60000 where N =engine speed in RPM and T = torque in Nm. The dynamometers give the engine torque from which the brake power can be calculated. Thus the brake mean effective pressure in an engine depends on torque only. Also, Brake power = Pmb*L*A*n / 60000. Therefore, Pmb = kT where k = 2π / L*A and k = 4π / L*A where L = stroke length, A = cross-sectional area of the cylinder, n = no. of working strokes per minute and, Pmb = brake mean effective pressure.
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