Question

Explain in detail the various types of errors.

Answer 1

The uncertainty in a measurement is called an error.

There are 3 types of errors namely –

1. Random error
2. Systematic error
3. Gross error.

1. Systematic errors – These are reproducible inaccuracies that are consistently in the same direction. These occur often due to problem that persists throughout the experiment. Systematic errors are further classified as

• instrumental error
• imperfection in experimental technique or procedure
• personal errors
• errors due to external causes
• least count error.

(a) Instrumental error: When an instrument is not calibrated properly at the time of manufacture instrumental errors may occur.

Example: If the measurement is made with a meter scale whose end is worn out the result obtained will have errors.

Correction – These errors can be corrected by choosing the instrument carefully.

(b) Imperfections in experimental technique or procedure: These errors arise due to limitations in the experimental arrangement.

Example: While performing experiments with a calorie meter, if there is no proper insulation, there will be radiation losses. This results in an error.

Correction – Necessary steps and corrections should be applied and followed while performing experiments.

(c) personal errors: These errors are due to individuals performing the experiments., maybe due to incorrect initial setting up of the experiment or carelessness of the individuals making the observation due to improper precautions.

(d) Errors due to external causes: The change in external conditions during experiments can cause errors in measurement.

Example: Changes in temperature, humidity, or pressure during measurement may affect the result of the measurement.

(e) Least count error: Least count is the smallest value that can be measured by the measuring instrument and the error due to this measurement is the least count error. The instrument’s resolution is the cause of the error. The error is half of the least value measured by the device.

Correction – Least count error can be reduced by using a high precision instrument for measurement.

(2) Random errors – Random errors may arise due to random and unpredictable variations in experimental conditions like pressure, temperature voltage supply, etc., Errors may also due to persona! errors by the observer. Random errors are sometimes called “Chance errors”.

Example: While measuring the thickness of a wire using a screw gauge, different readings are taken in different trails.

Correction – By taking the arithmetic mean of all readings observed may reduce the random error and the mean value is taken as the best possible true value.

(3) Gross errors – The error caused due to sheer carelessness of an observer is called gross error.

Examples: Improper setting of the instrument Making wrong observations without bothering about the sources of errors and precautions. Using wrong values in calculation Recording wrong observations

Correction – This error can be minimized only when the observer is careful and mentally alert.