Units and Measurement

1
Unit and Measurements Basic Terms
2
Measurement of physical quantities

• Basic standard is maintained to measure the
  physical quantities
• Major fundamental quantities are
• Length- meter (m)
• Mass- Kilogram (Kg)
• Time- Second (s)
• electric current- Ampere (A)
• thermodynamic temperature- Kelvin (K)
• amount of substance- Mole (mol)
• luminous intensity- Candela (cd)

3
About Derived Units

• Units are derived from the base or fundamental
  units such as volume (cubic meter).

4
About International System of units

• It is international standards created seven units
  having special standards to measure.
• Some of popular system to measure the physical
  quantities are
• CGS system
• FPS system
• MKS system
• SI system

5
Need of Dimensional Analysis

• Physical quantities are measured using
  fundamental or derived units
• Verify the equations and check their dimensional
  consistency
• helps in deriving relations between different
  physical quantities
• However consistency wont decide whether the
  given equation is true or wrong

6
Error in Measurement

• Occurrence of uncertainty in measuring a physical
  quantity
• Two types
• Systematic error negative or positive, static
• Random error occur irregularly and are not static

7
Other basic errors

• Least count error Occurs in measuring resolution
  of the practical instruments
• Absolute error magnitude of difference between
  the individual and actual measurement
• Mean Absolute Error arithmetic mean of all the
  absolute errors of the measured physical quantity

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