ERRORS AND UNCERTAINTIES

ERRORS AND UNCERTAINTIES

ERROR

All physical measurements are uncertain or imprecise to some extent. It is very difficult to remove all possible errors or uncertainties in a measurement. They can take place due to (i) negligence of a person (ii) inappropriate method.

There are two major types of errors which are as follows:

(1)- Random Error

(2)- Systematic Error   

(1)- Random Error

Random error is said to take place when repeated measurements of the quantity, give different values under the same conditions. It is due to some unknown reasons.

Reduction of random error:

The effect of random errors can be reduced by taking several readings of same quantity and then taking their mean (average) value. Thus average of a number of readings reduces the effect of random error.

(2)- Systematic Error

The systematic errors occur when all the measurements of a particular quantity are affected equally. These give consistent difference in the readings.

Occurrence of Systematic errors    

Systematic error can occur due to

(i)                  Zero error in measuring instruments

(ii)                Poor calibration of instruments or incorrect marking on the measuring instruments.

Reduction of systematic error:

Systematic error can be reduced by comparing the instruments with another instrument which is known to be more accurate. Thus, systematic error is reduced by applying a correction factor to all the readings taken on an instrument.

UNCERTAINTY

The uncertainty is also usually described as an error in an instrument. It can take place due to

(i)                  Inadequacy or limitation of an instrument

(ii)                Natural variations of the object being measured

(iii)               Natural defect of person’s senses.