PHYSICS FORM 1: TOPIC 3 - MEASUREMENT
Measurement is the process of assigning numbers to observations or events.
Physical Quantities
• Physical quantity is a property of a material that can be quantified by measurement.
There are two types of physical quantities namely.
• Fundamental quantities
Fundamental Quantities
• Are the basic physical quantities which cannot be obtained from other physical quantities.
Fundamental Quantities and their SI Unit
Length
• Is the distance between two points.
• The SI unit of length is metre (m).
• It is measured by metre rule, tape measure, Vernier calliper and micrometer screw gauge
Metre Rule
• Metre rule is a mainly wooden graduated in 100 centimeters or 1metre.
• The reading should be perpendicular to the mark otherwise the parallax error occurs
Parallax Error
• Is the apparent motion of one object related to another when the position of the eye is varied
Vernier Caliper
• Is an instrument used to measure length to the nearest accuracy of 0.01cm
• It is used to measure lengths to the range of 1.0 cm to about 12.0 cm
(a) The inside jaws are used to measure internal diameter
(b) The external jaws are used to measure external diameter
Scale of Vernier Calliper has two scales
• Main (Fixed) scale
• Vernier scale
NB:
• Fixed scale gives reading in centimeter (cm) or millimeter (mm).
• Vernier scale gives reading in hundredth of a centimeter (0.01cm) or thousands of millimeter (0.001mm)
• The reading should be taken in the parallel mark between fixed scale and vernier scales then convert it to cm or mm.
• Total reading is obtained by Summing up the main scale (M.S) and Vernier scale (V.S)
