Anna University 4th Semster Transducer Engineering 2 marks - Unit 1

Hello Friends, i am posting 4th Semester Transducer Engineering Unit - 1 2 Marks Questions and Answers for the past four years. Please make use of it and score well in your exam.

UNIT 1

TRANSDUCER ENGINEERING

1) What is instrument ?
It is a device for determining the value or magnitude of a quantity or variable.

2) Add 826 ± 5 to 628 ± 3 ?
N1 = 826 ± 5 ( = ± 0.605%)
N2 = 628 ± 3 ( = ± 0.477%)
Sum = 1,454 ± 8 (=± 0.55%)

3) Subtract 628 ± 3 from 826 ± 5 ?
N1 = 826 ± 5 ( = ± 0.605%)
N2 = 628 ± 3 ( = ± 0.477%)
Difference = 198 ± 8 (= ± 4.04%)

4) List three sources of possible errors in instruments ?
(i) Gross Error (ii) Systematic (iii) Random errors.

5) Define Instrumental error ?
These are the errors inherent in measuring instrument because of their mechanical structure.

6) Define limiting error ?
Components are guaranteed to be within a certain percentage of rated value. Thus the manufacturer has to specify the deviations from the nominal value of a particular quantity.

7) Define probable error.?
It is defined as r = ± 0.6745s where s is standard deviation.Probable error has been used in experimental work to some extent in past, but standard deviation is more convenient in statistical work.

8) Define Environmental error ?
These are due to conditions in the measuring device, including conditions in thearea surrounding the instrument, such as the effects of changes in temperature,humidity.

9) Define arithmetic mean.?
The best approximation method will be made when the number of readings would give the best result,
X = arithmetic mean
x1,x2,xn = readings taken

10) Define average deviation.?
By definition, average deviation is the sum of absolute values of the value deviations divided by the number of reading.

11) Define units.?
It is necessary to define a physical quantity both in kind and magnitude in order touche this information for further proceedings. The standard measure of each kind of physical quantity is named as the unit.

12) Define Standards ?
The physical embodiment of a unit of measurement is a standard. For example,the fundamental unit of mass in the international system is the kilogram and defined as the mass of a cubic decimeter of water at its temperature of maximum density of 4°c.

13) Mention the purpose of the measurement.?

  • To understand an event or an operation.
  • To monitor an event or an operation.
  • To control an event or an operation.
  • To collect data for future analysis
  •  To validate an engineer design.

14) What are the methods of measurement ?
  • Direct comparison method
  • Indirect comparison method

15) Define ODDs ?

The specification of limiting error is in itself uncertain because the manufacture himself is not sure about the accuracy because of the presence of random errors.

16) Classify Standards ?
  •  International standards
  •  Primary standards
  •  Secondary standards
  •  Working standards

17) Define transducer and give an example ?
Transducer is a device which converts one form of energy into electrical energy. A thermocouple converts heat energy into electrical voltage.

18) Classify transducer ?
On the basis of transduction form used:
  • As primary and secondary transducers
  •  As active and passive transducers
  • As analog and digital transducers
  • As transducers and inverse transducers

19) What is primary transducer?
Bourdon tube acting as a primary transducer senses the pressure and converts the pressure into displacement. No output is given to the input of the bourdon tube. So it is called primary transducer. Mechanical device can act as a primary transducer.

20) What is secondary transducer?
The output of the Bourdon tube is given to the input of the LVDT. There are two stages of transduction, firstly the pressure is converted into a displacement by the Bourdon tube then the displacement is converted into analog voltage by LVDT. Here LVDT is called secondary transducer. Electrical device can act as a secondary transducer.

21) What is passive transducer?
In the absence of external power, transducer cannot work and it is called a passive transducer. Example: capacitive, inductive, resistance transducers.

22) What is active transducer?
In the absence of external power, transducer can work and it is called active transducer. Example velocity, temperature, light can be transduced with the help of an active transducer.

23) What is analog transducer?
These transducers convert the input quantity into an analog output which is a continuous function of time. Thus a strain gauge, an LVDT, a thermocouple or a thermistors may be called analog transducer, as they give an output which is a continuous function of time.

24) Give the classification of units ?
  • Absolute units
  • Fundamental and derived units
  • Electromagnetic units
  • Electrostatic units

25) Define Primary fundamental and auxiliary fundamental units ?
Fundamental units in mechanics are measures of length, mass and time and those are fundamental to most other physical quantities and hence they are called Primary fundamental units.
Measures of certain physical quantities in thermal, electrical and illumination fields are also represented by fundamental units and are used only where those disciplines are involved and hence called auxiliary fundamental units.

26) Define unit of mass preserved at International Bureau of weights and measures at Severes near Paris ?
The unit of mass is represented by a material standard: the mass of International prototype kilogram consisting of platinum Iridium hollow cylinder.

27) Define static calibration ?
It refers to a process in which all the inputs(desired,modifying,interfering) except one are kept at some constant values.

28) Define Traceability ?
The ability to trace the accuracy of the standard back to its ultimate source in fundamental standards of National Institute of Science and Technology is termed “Traceability”.

29) What are random errors or residual errors?
The happenings or disturbances about which we are unaware and lumped together are called random errors or residual errors.Since these errors remain even after the systematic errors are taken care of,they are called residual errors.

30) Give one property of piezo-electric crystal ?
When a force is applied to piezo-electric crystals, they produce an output voltage.

31) Define an Inverse transducer. Give an example ?
A device which converts an electrical quantity into a non-electrical quantity. A piezo-electric crystal acts as an inverse transducer because when a voltage is applied across its surfaces, it changes its dimensions causing a mechanical displacement.

32) List the factors responsible in selection of a transducer ?
  • Operating principle
  • Sensitivity
  • Operating range.
  • Accuracy.

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