INTRODUCTION
1. What is meant by measurement?
Measurement means an act or the result of comparison between the
quantity and a
predefined standard.
2. Mention
the basic requirements of measurement.
The basic requirements of measurement are
i. The standard used for
comparison purpose must be accurately defined and should be commonly accepted.
ii. The apparatus used
and the method adopted must be provable.
3. State the
two methods for measurement.
The two methods of measurement are
i. Direct method and
ii. Indirect method.
4. State the function of measurement
system.
The measurement system consists of a transducing element which converts the quantity to be measured in an analogous form the analogous signal is then processed by some intermediate means and is then fed to the end device which presents the results of the measurement.
5. List
the three types of instruments.
The three types of instruments are:
i. Mechanical
Instruments
ii. Electrical
Instruments and
iii. Electronic Instruments.
6. Classify
the instrument based on their functions.
Instruments are classified into three types based on their
functions. They are
i. Indicating instruments
ii. Integrating instruments
iii. Recording instruments
7. Give any three applications of
measurement systems.
The applications of measurement systems are
i. Monitoring of
processes and operations.
ii. Control of processes and operations.
iii. Experimental
engineering analysis.
8. Why calibration of instrument is
important?
The calibration of all instruments is important since it affords
the opportunity to check the instrument against a known standard and
subsequently to errors in accuracy.
9. List the calibration procedure.
Calibration procedure involves a comparison of the particular
instrument with either.
A primary standard
A secondary standard with a higher accuracy than the instrument
to be calibrated or An instrument of known accuracy.
10. Define: Calibration
Calibration is defined as the process by which comparing the
instrument with a standard to correct the accuracy.
11. Mention the functions performed
by the measurement system.
The functions performed by the measurement system are
i. Indicating function
ii. Recording function
iii. Controlling function
12. List the functional elements of
the measurement systems.
The three main functional elements of the measurement systems
are:
i. Primary sensing element
ii. Variable conversion element
iii. Data presentation element
13. Write the characteristics of the
measurement system.
Characteristics of measurement system is divided into two
categories:
i. Static
characteristics
ii. Dynamic
characteristics
14. Write
the main static characteristics?
The main static characteristics are:
i. Accuracy
ii. Sensitivity
iii. Reproducibility
iv. Drift
v. Static error
vi. Dead zone
vii. Resolution
viii. Precision
ix. Repeatability
x. Stability
15. Define static error
Static error is defined as the difference between the true value
and the measured value of the quantity. Static error
= At – Am
where
Am =measured value of quantity
At =true value of quantity.
16. Define resolution
Resolution is defined as the smallest increment of quantity
being measured which can be detected with certainty being measured which can be
detected with certainty by an instrument.
17. Define threshold
Threshold is defined as the minimum value of the input at which
the output starts
changing/increasing from zero.
18. Define linearity
The linearity is defined as the ability to reproduce the input
characteristics symmetrically and linearly.
19. Define reproducibility
Reproducibility is defined as the degree of closeness with which
a given value may be repeatedly measured. It is specified in terms of scale
readings over a given period of time.
20. Define drift
Drift is defined as slow variation of reading from a fixed
value.
21. Define speed response
Speed response is defined as the rapidity with which a
measurement system responds to changes in measured quantity. It is one of the
dynamic characteristics of a measurement system.
22. Define fidelity
Fidelity is defined as the degree to which a measurement system
indicates changes in the measured quantity without any dynamic error.
23. Define dynamic error
Dynamic error is defined as the difference between the true
value of the quantity changing with time and the value indicated by the
measurement system if no static error is assumed. It is also called measurement
error. It is one the dynamic characteristics.
24.Define retardation delay
Retardation delay is defined as the retardation delay in the
response of a measurement system to changes in the measured quantity.
25. Define time delay
Time delay is defined as the response of the measurement system
begins after a dead zone after the application of the input.
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