errors and types of errors | class 9 physics federal board |systematic error and random error | NBF

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This video is about errors and its two types systematic and random error class 9 physics chapter 1 physical quantities and measurements of national book foundation.
Errors and Types of Errors

In physics, measurements are very important because all observations and calculations are based on them. However, no measurement is perfectly exact. The small difference between the measured value and the true value of a quantity is called an error. Errors do not mean mistakes; instead, they are natural and unavoidable in measurements due to limitations of instruments and human observation.

What is an Error?

An error is the difference between the true value of a physical quantity and its measured value.
For example, if the true length of a rod is 10.0 cm but it is measured as 9.8 cm, then an error of 0.2 cm exists. Errors can arise due to faulty instruments, wrong observation, or environmental conditions such as temperature and pressure.

Errors are broadly classified into systematic errors and random errors.

Systematic Errors

Systematic errors are errors that occur in a regular and predictable manner. These errors affect all measurements in the same direction, either increasing or decreasing the measured value.

Causes of Systematic Errors:

Instrumental errors: These occur due to defects or poor calibration of measuring instruments.
Example: A balance that shows 2 g even when nothing is placed on it will give wrong mass readings every time.

Observational errors: These occur due to incorrect observation by the observer.
Example: Reading a scale without keeping the eye perpendicular to the scale causes parallax error.

Environmental errors: These arise due to changes in surroundings such as temperature, humidity, or pressure.
Example: Expansion of a metal ruler on a hot day leads to incorrect length measurements.

Systematic errors can often be detected and reduced by proper calibration of instruments and careful observation.

Random Errors

Random errors are errors that occur in an irregular and unpredictable manner. These errors vary in size and direction and do not follow any fixed pattern.
Causes of Random Errors:
Unpredictable changes in experimental conditions
Limitations of human reaction time
Small fluctuations in measuring instruments
Examples of Random Errors:
Measuring the time of a pendulum using a stopwatch gives slightly different values each time due to human reaction delay.

Repeated temperature readings may vary due to slight air movements or changes in surroundings.

Random errors are uncontrollable and cannot be completely eliminated, but they can be reduced by taking repeated measurements and calculating the average value.

Difference Between Systematic and Random Errors

Systematic errors are consistent and occur in one direction.

Random errors are irregular and vary from reading to reading.

Systematic errors can be corrected, while random errors can only be minimized.

Conclusion

Errors are an unavoidable part of all measurements. Understanding the nature of systematic errors and random errors helps students perform experiments more accurately. By using good experimental techniques, careful observation, and repeated measurements, the effect of errors can be reduced, leading to more reliable results.

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