O-Level Physics Error & Uncertainty Masterclass
Download printable cheat-sheet (CC-BY 4.0)30 Nov 2025, 00:00 Z
Reviewed by
Chee Wei Jie
Academic Advisor (Physics)
TL;DR\ SEAB’s 2026 Physics syllabus expects you to quote readings to the correct precision, propagate uncertainties, and discuss limitations for ACE. Use absolute + percentage uncertainties, keep significant figures consistent with instrument resolution, and tie every ACE statement to how an error changes your conclusion.\ Build a commentary template: state result ± uncertainty, compare with accepted value, identify dominant error, propose a realistic fix (syllabus link currently redirects; keep using the 6091 PDF as ground truth, checked 2025-11-30).
Keep Your Physics Practical Stack On Track
Use our O-Level Physics Experiments hub to find companion drills for every Paper 3 skill before you attempt these walkthroughs.
1 | Precision rules every candidate must memorise
- Instrument dictates precision: Quote metre-rule readings to 0.1 cm, vernier caliper to 0.01 cm, micrometer to 0.001 cm, and stopwatches to 0.1 s unless otherwise stated (Section 4, SEAB 6091 syllabus PDF).\
- Write what you record: Raw tables must show units in headings (
Length / cm) and use consistent decimal places aligned with the measuring tool.\ - Calculated quantities follow the weakest link: When you compute density, resistance, or refractive index, round to the same number of significant figures as the least precise raw input.
✅ Quick check: before leaving a table, scan the decimal places column by column. Any mix like12.0vs12.00means a lost mark in PDO.
2 | Uncertainty toolkit (with sample numbers)
| Scenario | Resolution | Absolute uncertainty | Example reading | Percentage uncertainty |
| Metre rule length | 0.1 cm | ±0.1 cm | 52.3 cm |
