In general, the errors in measurement can be broadly classified as
(a) systematic errors and
(b) random errors.
`text(Systematic errors :)`
The systematic errors are those errors that tend to be in one direction, either positive or negative. Some of the sources of systematic errors are :
(a) `text(Instrumental errors)` that arise from the errors due to imperfect design or calibration of the measuring instrument, zero error in
the instrument, etc. For example, the temperature graduations of a thermometer may be inadequately calibrated (it may read 104 -C at the boiling point of water at STP whereas it should read 100 -C); in a vernier callipers the zero mark of vernier scale may not coincide with the zero mark of the main scale, or simply an ordinary metre scale may be worn off at one end.
(b) `text(Imperfection in experimental technique or procedure)` To determine the temperature of a human body, a thermometer placed under the armpit will always give a temperature lower than the actual value of the body temperature. Other external conditions (such as changes in temperature, humidity, wind velocity, etc.) during the experiment may systematically affect the measurement.
(c) `text(Personal errors)` that arise due to an individual-s bias, lack of proper setting of the apparatus or individual-s carelessness in taking observations without observing proper precautions, etc. For example, if you, by habit, always hold your head a bit too far to the right while reading the position of a needle on the scale, you will introduce an error due to parallax.
Systematic errors can be minimised by improving experimental techniques, selecting better instruments and removing personal bias as far as possible.
`text(Random errors :)`
The random errors are those errors, which occur irregularly and hence are random with respect to sign and size. These can arise due to random and unpredictable fluctuations in experimental conditions (e.g. unpredictable fluctuations in temperature, voltage supply, mechanical vibrations of experimental set-ups, etc), personal (unbiased) errors by the observer taking readings, etc. For example, when the same person repeats the same observation, it is very likely that he may get different readings everytime.
`text(Least count error :)`
The least count error is the error associated with the resolution of the instrument. For example, a vernier callipers has the least count as 0.01 cm; a spherometer may have a least count of 0.001 cm. Least count error belongs to the category of random errors but within a limited size; it occurs with both systematic and random errors.
In general, the errors in measurement can be broadly classified as
(a) systematic errors and
(b) random errors.
`text(Systematic errors :)`
The systematic errors are those errors that tend to be in one direction, either positive or negative. Some of the sources of systematic errors are :
(a) `text(Instrumental errors)` that arise from the errors due to imperfect design or calibration of the measuring instrument, zero error in
the instrument, etc. For example, the temperature graduations of a thermometer may be inadequately calibrated (it may read 104 -C at the boiling point of water at STP whereas it should read 100 -C); in a vernier callipers the zero mark of vernier scale may not coincide with the zero mark of the main scale, or simply an ordinary metre scale may be worn off at one end.
(b) `text(Imperfection in experimental technique or procedure)` To determine the temperature of a human body, a thermometer placed under the armpit will always give a temperature lower than the actual value of the body temperature. Other external conditions (such as changes in temperature, humidity, wind velocity, etc.) during the experiment may systematically affect the measurement.
(c) `text(Personal errors)` that arise due to an individual-s bias, lack of proper setting of the apparatus or individual-s carelessness in taking observations without observing proper precautions, etc. For example, if you, by habit, always hold your head a bit too far to the right while reading the position of a needle on the scale, you will introduce an error due to parallax.
Systematic errors can be minimised by improving experimental techniques, selecting better instruments and removing personal bias as far as possible.
`text(Random errors :)`
The random errors are those errors, which occur irregularly and hence are random with respect to sign and size. These can arise due to random and unpredictable fluctuations in experimental conditions (e.g. unpredictable fluctuations in temperature, voltage supply, mechanical vibrations of experimental set-ups, etc), personal (unbiased) errors by the observer taking readings, etc. For example, when the same person repeats the same observation, it is very likely that he may get different readings everytime.
`text(Least count error :)`
The least count error is the error associated with the resolution of the instrument. For example, a vernier callipers has the least count as 0.01 cm; a spherometer may have a least count of 0.001 cm. Least count error belongs to the category of random errors but within a limited size; it occurs with both systematic and random errors.