Experiment 1: Errors, Uncertainties and Measurements
Kendrick Don Reyes, Myrr Kea Rostrata, Josemarie Emmanuel Roxas, Lindley Susi, Jessica Tabuzo
Department of Biological Sciences
College of Science, University of Santo Tomas
España, Manila Philipines
In this experiment, different measuring devices were used, namely the vernier calliper, micrometer calliper, foot rule, and the electronic gram balance. These devices were used to obtain the mean diameter, volume, mass, and the experimental value of density of the sphere of known composition. 1. Introduction
Measurement is the process or act of determining the size, length, quantity, etc. of something being observed or measured. The units of measurement evolved and changed greatly since the day it was made by humans. In different places, these measurements can vary and could well be different from each other. Thus, standards are used nowadays so that we can have a concrete basis and this also prevents fraud or the cheating of somebody especially in business matters. There are different systems of measurement used. We have this CGS system or known as centimeter-gram-second system which is a metric system derived from the meter-kilogram-second system or mks system. It uses centimeter (c) for
length, gram (g), second (s) for time, dyne for force, and erg for energy. The metric system has become a common system for weights and measures. Its simplicity is the reason why scientists use this system of measurement. You can easily change one unit of measure into another. The units of measurement in this system are all based on decimals. By simply moving the decimal point to the right or left, depending on whether the unit is being decreased or increased, you can change its unit. Greek decimal prefixes like deca, hecto, kilo is used to express units of ten multiples or greater. Despite setting all of these standards, one’s measurement can never be exact and can always have a certain amount of error. When a measurement is done, the outcome could depend on several factors like the measuring system, the procedure taken, the execution of techniques of the operator, and the condition of the environment (Bell, 1999). This dispersion of values that can be attributed to a measured quantity is what we call as measurement uncertainty. The flaws in measurement can come from the measuring instrument itself due to aging, wearing, poor readability or even noise. The item being measured, if not stable, can produce uncertainties.
There are two types of measurement error, systematic error and random error. Imperfect calibration of instrument, its age, wear, and tear, throughout the years which lead to errors can be classified as a systemic error. When you measure the weight of an object using a particular balance which is improperly tared and you get a certain amount of grams higher for all your mass measurements is an example of systematic error. Random errors, on the other hand, are caused by unknown and unpredictable changes in the experiments. Irregular changes in the environment can usually cause this and as well as the random noise on an electrical device (Exell).
The precision of a measurement is determines the exactness or accuracy of a number of measurements and how the same quantity agrees with each other. Accuracy tells the correctness, veracity or truthfulness of a measurement. The closer the measurement to the accepted value, the more accurate it is. In this experiment, the group aims to achieve the following objectives: (1) to study errors and how they propagate in simple experiment, (2) to determine the average deviation of a set of experimental values, (3) to determine the mean of a set of experimental values as well as a set of average deviation of the mean, (4) to familiarize the students with the vernier caliper, micrometer caliper, and the foot rule, (5) to compare the accuracy of these measuring devices, (6) to...
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