Applied Science, Scientific Method, Measurement and Experimental Skills
Applied Science, Scientific Method, Measurement and Experimental Skills
This domain tests how scientific questions are investigated and how observations are measured reliably: hypothesis, variables, SI units, instruments, least count, errors and safe laboratory practice.
Core rules
- Scientific method: observation → question → hypothesis → controlled experiment → data analysis → conclusion. A hypothesis must be testable and falsifiable.
- Independent variable is changed; dependent variable is measured; controlled variables are kept constant.
- SI base units include metre, kilogram, second, ampere, kelvin, mole and candela.
- Least count is the smallest measurement an instrument can read. Vernier least count = 1 main-scale division − 1 vernier-scale division; for 1 mm main scale and 10 vernier divisions, it is 0.1 mm.
- Random errors affect precision; systematic errors affect accuracy. Parallax error is avoided by reading at eye level.
- Record measurements with correct units and reasonable significant figures; repeat readings and average them.
Worked example
A vernier calliper has a main scale in millimetres and 10 vernier divisions. Least count = 1 mm/10 = 0.1 mm. The main scale reads 12 mm and the 4th vernier division coincides with a main-scale line. Vernier reading = 4 × 0.1 = 0.4 mm. Total = 12.0 + 0.4 = 12.4 mm. The zero error must be subtracted if the instrument is not correctly zeroed.
Traps
Do not write a measurement without its unit. Do not confuse least count with zero error. Changing two variables at once prevents a valid cause-and-effect conclusion. A precise set of readings can still be inaccurate if there is a systematic error. Heat and chemicals require goggles and proper ventilation.