University:
Arizona State University
Course:
PHYS 102 | Introductory Physics I
Academic year:

2024
Views:

318

Pages:

5
Author:

Mohammed N.

Random Errors Random errors may be reduced by the use of certain statistical tools. Let's suppose we want to measure any physical quantity. In order to reduce the influence of random errors it is necessary to be able to make many measurements of the same quantity: it is therefore necessary that the physical quantity we want to measure is always reproducible under the same conditions. Arithmetic Mean: This is the total sum of the measurements, divided by the number of measurements made. Arithmetic mean is to find an approximation of the real value of the measured quantity, the accuracy increases as the number of measurements increases. Absolute Error It is the difference in module (the final result is always positive) between the measured value and the actual value: it shows how much the collected data deviate from the measured value Relative error The relative error is the ratio of the absolute error to the average of the measurements. The percent error is the percentage indication of the relative error. Percent error: The relative error can be expressed as a percentage of the measurement value; this is how the percent error is defined, which is obtained by multiplying the relative error by 100: so it is like calculating the amount of the error made if the value of the quantity measured is 100. International System of Units The International System of Units (abbreviated to SI) is a treaty, where basic physical quantities - called base quantities - and corresponding units of measurement have been introduced and defined. From the International System of Units all other quantities and all other units of measurement are obtained The International System of Units provides for the use of 7 units of measurement for 7 base quantities. For each unit of measurement the symbol to be used universally, the rules on the use of the various symbols and the composition of the derived units of measurement from the base ones have also been established. From the base quantities we can derive the derived quantities. Prefixes in the International System of Units When dealing with very large or very small sizes, we can use the following prefixes which represent a conversion factor given by a certain integer power of 10. Here are all listed, respectively with Prefix, Symbol and Factor yotta- Y- 10^24 zetta- Z-10^21 exa- E-10^18 map- P-10^15 tera- T-10^12 giga- G-10^9 mega- M- 10^6 kilo- k- 10^3 etto-h-10^2 kilo- k- 10^3 etto-h-10^2 deca-da- 10^1 decide-10^-1 centi- c- 10^-2 milli-m-10^-3 micro- μ- 10^-6 nano- n- 10^-9 peak-p-10^-12 femto-f- 10^-15 act-a-10^-18 zepto-z- 10^-21 yocto-y- 10^-24