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Units PowerPoint Presentation

Units

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Units

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  1. Units • Definition: The standard measure of each kind of physical quantity is called a UNIT. • Measurement: Measurement implies comparison with a standard value. The magnitude of a physical quantity can be written as: Numerical ratio x Units

  2. Types of Units • In Science and Engineering there are tow kinds of Units: • Fundamental Units • Derived Units • Units to measure Length, Mass and Time are known as Fundamental Units. • All other units which can be expr3esseed in terms the fundamental units are called Derived Units.

  3. Dimension • Definition: • The unique quality of every quantity which distinguishes it from all other quantities is called dimension. • Dimensional symbols for Length, Mass and Time are: • L, M, T • All Derived units would be defined as multiple of fundamental dimensions: • Volume….L3 • Speed …..LT-1 • Acceleration …..LT-2

  4. System of Units • British System of units describes fundamental in centimeter, grams and seconds and therefore called CGS system. • The System that uses Meter , Kilogram and Second is called MKS. • International System of Units…SI mostly uses MKS units but is rationalized in application.

  5. Types of SI • SI units are divided into Three: • Base Units • Derived Units • Supplementary Units

  6. Base Units

  7. Derived SI Units… 1

  8. Derived SI Units…..2

  9. SI derived units with special names

  10. SI derived units with special names

  11. SI derived units with special names

  12. SI derived units with special names

  13. Definition related to Instruments • True or actual Value: That magnitude to measuring system which can be approached and never evaluated is termed as True Value. • Indicated Value: The value which is indicated by the instrument. • Correction: The revision applied to the critical value so that the final result obtained improves the worth of result is called correction. • Overall error: The difference of sacle reading and true value. • Range: The region between the limits an instrument can operate.

  14. Definition related to Instruments • Sensitivity: The ratio of output response to a specified change in the output is called sensitivity. • Minimum measurable change in variable is called Resolution sensitivity. • Lowest level of measured variable that produces effective response is called Threshold sensitivity. • Scale Sensitivity: The ratio of change in scale to corresponding change in pointer deflection. • Scale Readability: