1 4 UNDERSTANDING MEASUREMENTS INTRODUCTION TO PHYSICS MEASUREMENT

MEASUREMENT � Determination of the actual value for particular physical quantity.

CONSISTENCY Ability of a measuring instrument to give readings with very small deviation or

EXAMPLE Mean value group A = 13. 97 s Mean value group B =

ACCURACY Ability of a measuring instrument to give readings nearest or almost equal to

SENSITIVITY � Ability of a measuring instrument to detect a very small changes in

TYPE OF EXPERIMENTAL ERRORS � 2 1. 2. main types of errors Systematic errors

Systematic errors Differences Random errors Errors caused by the condition of the measuring instrument

SYSTEMATIC ERROR : ZERO ERROR Is the error in an instrument that does not

VERNIER CALLIPER Measure length with an accuracy of up to +0. 1 mm (0.

MICROMETER SCREW GAUGE � To measure thickness or diameter of small objects.

THE PART OF MICROMETER SCREW GAUGE AND ITS FUNCTION

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1. 4 UNDERSTANDING MEASUREMENTS INTRODUCTION TO PHYSICS

MEASUREMENT � Determination of the actual value for particular physical quantity.

CONSISTENCY Ability of a measuring instrument to give readings with very small deviation or no deviation from the mean value. Consistency of a measuring instrument can be improved by: Taking a reading with caution Eliminating parallax errors Using the instrument which is not defective

EXAMPLE Mean value group A = 13. 97 s Mean value group B = 14. 30 s

ACCURACY Ability of a measuring instrument to give readings nearest or almost equal to the actual value Accuracy of a measurement can be improved by; Repeating the measurement Avoiding zero errors Avoiding parallax errors Using the measuring instrument with a higher sensitivity

SENSITIVITY � Ability of a measuring instrument to detect a very small changes in the quantity being measured.

TYPE OF EXPERIMENTAL ERRORS � 2 1. 2. main types of errors Systematic errors Random errors

Systematic errors Differences Random errors Errors caused by the condition of the measuring instrument or environment when measurements are taken. Definition Errors due to mistakes made when measurements are taken either through incorrect positioning of the eye or sudden change of environmental factors • Zero error • Incorrect calibration of instrument • Improper use of instrument Example • Parallax error • Errors in counting • Natural errors: q changes in temperature, humidity, or wind Proper calibration or adjust the instrument frequency Overcome problems of error Repeat the measurement and take the average or mean value of readings

SYSTEMATIC ERROR : ZERO ERROR Is the error in an instrument that does not show zero reading when it should show zero reading (when not measuring any quantities)

RANDOM ERROR : PARALLAX ERROR

MEASURING INSTRUMENTS

VERNIER CALLIPER Measure length with an accuracy of up to +0. 1 mm (0. 01 cm)

ZERO ERROR

EXAMPLE

MICROMETER SCREW GAUGE � To measure thickness or diameter of small objects.

THE PART OF MICROMETER SCREW GAUGE AND ITS FUNCTION