In measuring instruments errors occurs from different sources . They're mainly classified into three.
1. GROSS ERRORS
2. SYSTEMATIC ERRORS
*This systematic errors are further classified into three they are,
1-Observational errors
2-Instrumental errors
3-Environmental errors
3. RANDOM ERRORS
2. SYSTEMATIC ERRORS
*This systematic errors are further classified into three they are,
1-Observational errors
2-Instrumental errors
3-Environmental errors
3. RANDOM ERRORS
GROSS ERRORS
This errors mainly happens due to the problem in calculating results of the measurements , when taking the instrument readings and the time of noting and recording of data. Gross errors cant be eliminate completely.
Gross errors cant be analysed mathematically cause their amount may different. Still there are two methods to avoid this errors,they are...
1) Be careful while recording and taking the reading(ie. Read the data precisely and accurately).
2) Take the reading for three or more times to get a constant value of the quantity what we are measuring.
Manufacturer of the instrument can avoid the error upto an extend.
Gross errors cant be analysed mathematically cause their amount may different. Still there are two methods to avoid this errors,they are...
1) Be careful while recording and taking the reading(ie. Read the data precisely and accurately).
2) Take the reading for three or more times to get a constant value of the quantity what we are measuring.
Manufacturer of the instrument can avoid the error upto an extend.
SYSTEMATIC ERRORS
This errors are of three types environmental, instrumental, observational errors. This errors can be found only if the experiment is repeated for many times under different conditions and different methods because this errors cant find directly.
This errors are of three types environmental, instrumental, observational errors. This errors can be found only if the experiment is repeated for many times under different conditions and different methods because this errors cant find directly.
1. Environmental errors
This kind of errors occur due to the external conditions of the instrument . smoke, dust, moisture, external magnetisation, electro static force, humidity, vibration, pressure, temperature are the some environmental conditions effect this error.
These errors can be reduced and eliminated by following steps...
1) calibrated under local condition.
2) control the pressure, temperature, humidity to a value that which the instrument is assembled and calibrated.
3) calibrate and make the reading of instrument correct.
This kind of errors occur due to the external conditions of the instrument . smoke, dust, moisture, external magnetisation, electro static force, humidity, vibration, pressure, temperature are the some environmental conditions effect this error.
These errors can be reduced and eliminated by following steps...
1) calibrated under local condition.
2) control the pressure, temperature, humidity to a value that which the instrument is assembled and calibrated.
3) calibrate and make the reading of instrument correct.
2. Instrumental errors
This kind of errors occurs due to instrument misusing, loading effects, inborn shortcomings of the instrument. This type of errors are inborn errors due to the manufacturing defect or problem or even some small conditions , improper calibration etc. Weak selection and improper maintenance of the instrument is also a cause. Some unresolvable physical phenomenons like friction, capillary attractions also may may cause error.
Assembly error, this kind of errors mainly related to the reading scale and pointer etc.
Assembly error, this kind of errors mainly related to the reading scale and pointer etc.
3. Observational errors
This error causes due to the carelessness of the observer or the operators. some of the things which leads to observational error.
i) wrong recording.
ii) wrong observation and wrong reading.
iii) miss understanding of observed reading.
iv) incorrect conversion of readed values.
* Modern Instruments are in digital form which completely eliminates the observational errors by producing digital output in digits etc.
i) wrong recording.
ii) wrong observation and wrong reading.
iii) miss understanding of observed reading.
iv) incorrect conversion of readed values.
* Modern Instruments are in digital form which completely eliminates the observational errors by producing digital output in digits etc.
RANDOM ERRORS
This error happens accidentally, they are small and independent. This type of errors can't be predicted and assumed by any kind of measuring instruments information.
Causes of this errors.
1: Mechanical vibration.
2: Friction and backlash instrument movement.
3: Parallax error caused in between scale and pointer.
4: Correct dimension and area of the scale and pointer divisions.
5: Elastic members Hysteresis.
Causes of this errors.
1: Mechanical vibration.
2: Friction and backlash instrument movement.
3: Parallax error caused in between scale and pointer.
4: Correct dimension and area of the scale and pointer divisions.
5: Elastic members Hysteresis.
Some of the sources of errors
1- Noise :- signals which conveys no information is called noise error
This errors can be reduced by filtering and right selection of instruments.
2- Response time.
3- Design limitations :- Features like friction and resolving power during design of the instrument causes to this errors.
4- Energy exchanging during interaction.
5- Transmission:- There is chance to attenuation of the signal when the signal is transmitted from primary sensing device to the indicator.
6- Deterioration of instrument.
7- Ambient influences on measuring instruments.
8- observational errors and clarification.
This errors can be reduced by filtering and right selection of instruments.
2- Response time.
3- Design limitations :- Features like friction and resolving power during design of the instrument causes to this errors.
4- Energy exchanging during interaction.
5- Transmission:- There is chance to attenuation of the signal when the signal is transmitted from primary sensing device to the indicator.
6- Deterioration of instrument.
7- Ambient influences on measuring instruments.
8- observational errors and clarification.
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