SCIENCE_PHYSICS
ACCURATE MEASUREMENT IS ESSENTIAL
Introduction
The process of comparing unknown quantities with known standard quantities of similar kind is measurement. Simply it is the action of measuring something. If the object or the quantity to be measured is not accessible for direct comparison, it is converted or transduced into analogous measurement signal. The process involves the interaction between object and observer or the observing instrument. During this process there is always an exchange of energy which is negligible and can be studied under the mathematical process of limit and accuracy.
Quantification, quantifying, calculation, computation, mensuration, estimation, evaluation, weighing and sizing are the various synonyms of measurement.
Measurement Theory
Measurement theory is the study of how numbers are assigned to objects and phenomenon and its concerns include the kinds of things that can be measured, how different measures relate to each other and the problem of error in the measurement process
History of Measurement
The history of measurement began from the fourth century BC. During this time a theory of magnitudes was developed by Greek mathematician Eudoxus of Cnidus. Early Babylonians and Egyptians records and the Hebrew Bible indicate the length was first measured by the forearm hand or finger and the time was measured by the periods of sun moon and other heavenly bodies. In order to measure the capacity/ volume of the clay or metal vessels they were filled with plant seeds and later counted to measure the volume. As the time passed to bring more accuracy in the measurement of mass and weight seeds and stones were used as the standard masses. In 18 th century the measurement process was first incorporated into social science by Jeremy Bentham, a British Utilitarian moralist, by introducing the theory for the measurement of value.
Approximation in Measurement:
Though measurement is a physical activity it is always not concerned with the exact solution to a problem. Approximation is the quality of the state of being close or near to the value. In these instances approximate mathematical expressions are good enough for practical purposes. Sometimes approximation is also called guesstimates. Some examples of approximations are shown below.
Sometimes approximation and estimation seem to be similar in meaning, in fact there are some differences. Estimation refers to roughly calculated data derived from imperfect data, while approximate is to carry out advance near to; cause to approach.
Unit
How do we measure something really, really small or big?
If we are measuring the distance between the Sun then not by meter rod. Units must exist that can describe sizes many times bigger than the biggest marking a meter rod.
The units that are used during the measurement process are based on the International System of Units (SI), which is a form of metric system( base of 10). The SI unit is the abbreviated form of French term Le Système international d'unités.
As the technology of measurement processes progresses, new units are evolved and their definitions are changed through international agreement among many nations. The SI unit is made up of seven base units. These base units are also called fundamental units The seven units are tabulated as below. From these seven fundamental units several other units are derived which are classified under derived units.
Use of prefix in SI Unit
Several prefixes are added to the SI Unit to make multiple of the original unit. For example kilo is the prefix that stands for a multiple of thousand while mili stands for the multiple of a thousandth.
tera, giga, mega, kilo, hecto, deca, deci, centi, mili, micro, nano, pico are the prefixes used to add to the SI Unit to make multiple of the original unit. All prefixes are the multiple of 10.
Practise Section
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