Errors in Measurement
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| (Erros in measurement) |
What are Errors in Measurement?
An error is defined as the dissimilarity between the calculated measurement and the exact measurement.
For example, if two persons are using a same instrument for measuring it is not sure that both are getting the same outcomes. There will be a slight differences between the measured output of those two persons. Those slight differences are called as errors.
In general, the error is the difference between the true value and measured value of the measurement.
In order to reduce the errors the instrument must be calibrated in a right way.
Calibration is the act of comparison of Measurements to maintain the accuracy of certain measurements. It is the process used for configuration of instruments to provide results within the acceptable range of tolerance. To know more about calibration process, read our article titled, "Calibration of measuring instruments" in that we are clearly deatiled about calibration process.
Terminology of Measurement
Before we are going to know about the errors types we must know some of the main terminology and basics of engineering Metrology.
The quality of the measurement can be described by using the following terms such as Precision, accuracy, sensitivity, repeatability.
Errors Types
The errors in measurement are caused by various factors and the errors are classified in the following types.
1. Systematic Errors
2. Gross Errors
3. Random Errors
Systematic Errors
The systematic errors are further classified into three types. They are
1. Observational Errors
2. Environmental Errors
3. Instrumental Errors
Observational Errors
The observational error occurs because the false study of instrument reading. There are many sources for this kind of errors to occur.
The main source of this error is Parallax effect. Parallax meaning 'alternation'. The parallax is defined as the displacement or the difference in the appropriate position of an object viewed in two different sides of views.
For example, if you took reading by using an ammeter, the indicator of the ammeter will have very small oscillation over the surface of the scale. As a result of this a fault happens above the indicator except the original value.
In order to reduce this parallax error extremely precise meters along with reflected scales are being used.
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| (Observational error) |
Environmental Errors
Environmental errors occurs due to the outside environmental situation of the measuring instruments. These errors mostly occurs due to change in certain atmospheric conditions like temperature, moisture, humidity etc.,
There are some efforts to reduce these environmental errors. They are as follows
- The evaluation should be finished within the stable environmental situation.
- Always prefer to use the instrument which is not affected by the environmental issues such as temperature, pressure, humidity, etc.,
Instrumental Errors
Instrumental errors will happen due to some of the imitation of Devices wgich are being used for measuring. These errrors may occur due to the operation taken while measuring using the instrument or may be at the calculation. These errors will have impact in the value all the way from low level to high level.
Improper observer of the instrument
The errors on the instrument may happens because of the mistakes made the operator of the instrument. If an operator operates an advanced instrument without proper knowledge about that instrument will have a drastic effect. The improper observation may not cause harm to the instrument but it will cause all the other possible issues.
Gross Errors
This kind of errors are defined as the physical analysis error. This error can be occur due to the occurrence of mistake in calculating or recording the output values made by the observer. This error will occur in allover the experiment, wherever the observer records aor calculate with the different value other than the real ones. With proper knowledge these kinds of error can be predictable and also it can be easily corrected.
To avoid these error careful recording and calculations must be done throughout the experiment or work. It is also suggested to take two or more readings by different and accumulate it together to eliminate these gross errors.
Random Errors
The random error will occur due to the oscillations or vibrations in the apparatus which is being measured. This kind of error will be in the instrument at most of the times.
These errors are cleared by taking careful recording throughout the experiment . It is also suggested to take two or more readings by different and accumulate it together to eliminate these gross errors.
The Measurement Errors Calculation
The errors in measurement doesn't stands that the taken measurement were wrong instead it stands for that the device is not accurate enough for measuring. The errors are eliminated in three types of calculations namely
- Absolute error
- Relative error
- Percentage error
Absolute error
The absolute error is defined as the variation between actual value and measured value of the measurement.
Absolute error = Actual Value - Exact Value
Percentage error
The percentage error is defined as the percentage ratio of absolute error and the exact value.
[(Actual value-Exact value) / Exact value] x 100
Relative error
The relative error is defined as the ratio of the absolute error and the actual value of the measurement.
Relative Error = Absolute error/actual value
What are errors?
An error is defined as the dissimilarity between the calculated measurement and the exact measurement.
How many types of errors are there?
The errors in measurement are caused by various factors and the errors are classified in the following types.
1. Systematic Errors
2. Gross Errors
3. Random Errors
what are gross errors
This kind of errors are defined as the physical analysis error. This error can be occur due to the occurrence of mistake in calculating or recording the output values made by the observer
what are the types of systematic errors
Observational errors, environmental errors, instrumental errors
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Conclusion
That's all about the errors in measurement and errors types, I hope you understand the definitions, types of errors in measurement.
If you have any queries or doubts or need improvements in this article put that in the below-mentioned comments section we will reply and rectify as fast as possible.
Superb explanation
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