Description of Errors in Measurement

Errors in Measurement

The following errors are likely to occur in the measurement of a physical quantity:

(1) Systematic Errors (arise due to known causes. The experimenter has control over the errors)
(2) Random Errors (arise due to unknown causes. The experimenter has no control over the errors)

(1) Systematic Errors:

When a measurement always has the same error (i.e. the nature or sign of the error is always of the same type, positive or negative), it is called systematic error.

Systematic errors occur due to known causes. These errors can be removed by knowing the causes.

Types of Systematic Errors:

(i) Constant Errors: If the measuring instrument is faulty from the point of view of its structure or design. That is, if the measurement marks made on the measuring instrument are wrong (faulty graduations), then by using such an instrument the error is always the same in all the observations. Such an error is called a constant error.

To remove static errors, an error-free measuring instrument should be used in place of the faulty measuring instrument and if this is not possible, then the nature of the error in the faulty instrument should be determined and measurements should be made as many times as possible.

(ii) Errors Due to Instruments: Such measuring instruments are error-free from the point of view of structure or design, but their excessive use causes defects in these instruments. Like zero error in vernier calipers or screw gauges, etc. Before starting the observation, such errors are found in all the measuring instruments used so that the final result of the measurement can be accurate.

(iii) Personal Errors: Those errors which arise due to the carelessness of the experimenter or the person doing the measurement are called personal errors. It does not depend on measuring instruments. This error can be reduced by increasing caution and taking readings correctly.

(iv) Errors caused by external factors (Errors due to External Reasons): Errors caused in observation due to changes in pressure, temperature, humidity, air velocity, etc. while taking observations are called errors caused by external factors.

These types of errors can be eliminated by adopting appropriate precautions and making possible arrangements to control environmental change. Can be done.

(2) Random Errors:

Such errors over which the experimenter has no control are called irregular errors. If the temperature, pressure, or humidity of the environment suddenly changes rapidly during observation or the supply voltage changes suddenly in any electrical experiment or the value of the earthquake exceeds the normal limit, then such changes have different effects in different experiments which affects the value of observation. These errors can be eliminated to a great extent by taking measurements several times and finding their average. Actual value can be found.