Physical Quantities And Measurement Techniques | Motion, Forces and Energy | O Level Physics 5054 & IGCSE Physics 0625 | Free Notes For Preparation

🔹 Ruler

• Range: Up to 30 cm

• Precision: ±0.5 mm

• Use for: Straight edges (e.g. books, tables)

• Best Practices:

  • Align 0 mark with object’s edge

  • Eye at same level → avoid parallax error

  • Measure in mm for higher precision

🔹 Measuring Tape

• Range: Several metres (1–50 m)

• Precision: ±1 mm (varies with tape quality)

• Use for: Large or curved objects (e.g. body, walls)

• Tips:

  • Keep tape flat and taut

  • Avoid bends and twists

  • Use assistant if long distance

🔹 Micrometer Screw Gauge (Analogue)

• Range: 0–25 mm (standard)

• Precision: ±0.01 mm

• Use for: Wire diameter, metal sheet thickness

• Structure:

  Part	Function
  Anvil	Fixed end
  Spindle	Moves to grip object
  Sleeve scale	Main mm scale
  Thimble scale	Rotating 0.01 mm scale
  Ratchet	Ensures constant pressure

   

• Reading Example:

  • Sleeve: 5.5 mm

  • Thimble: 28 → 28 × 0.01 mm = 0.28 mm

  • Final Reading = 5.5 + 0.28 = 5.78 mm