Physical World and Measurement — Class 11 ISC Physics revision notes
A 6-page visual revision sheet for Physical World and Measurement, written for Class 11 ISC Physics. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.
Page 1 as PDF
Physical World and Measurement in one look
the units physics agreed on, how many digits an answer may keep, and what dimensions can prove
A unit is a reference standard, chosen not discovered
- physics is a science of measurement, and a measurement is a comparison with an agreed standard, so the number alone means nothing without its unit
- a good standard is invariable, reproducible anywhere, imperishable and convenient in size, which is why no physical artefact is used any more
- four systems appear in this course: CGS, FPS, MKS and MKSA, which adds the ampere to MKS
- SI is MKSA extended to seven base units, and it is the only system an answer should be written in unless the question says otherwise
The seven SI base units, and the two supplementary ones
| Quantity | Unit | Symbol |
|---|---|---|
| length | metre | m |
| mass | kilogram | kg |
| time | second | s |
| electric current | ampere | A |
| thermodynamic temperature | kelvin | K |
| amount of substance | mole | mol |
| luminous intensity | candela | cd |
| plane angle (supplementary) | radian | rad |
| solid angle (supplementary) | steradian | sr |
The four systems side by side
| System | Length | Mass | Time | Current |
|---|---|---|---|---|
| CGS | centimetre | gram | second | not included |
| FPS | foot | pound | second | not included |
| MKS | metre | kilogram | second | not included |
| MKSA / SI | metre | kilogram | second | ampere |
Page 1 of 6. The full sheet, all 6 pages, opens free in the app.
What this Physical World and Measurement sheet covers
- A unit is a reference standard, chosen not discovered
- The seven SI base units, and the two supplementary ones
- The four systems side by side
- Writing a unit correctly is worth a mark
- Prefixes, atto to tera
- Units outside SI that the paper still uses
- Measuring what no instrument reaches
- Errors, and the three kinds that behave differently
- Reporting an error, in the forms the paper asks for
- Combining errors, which is where the marks are
- sum or difference
- product or quotient
- power
- Significant figures, and where they come from
- Worked, one line each
- Dimensions, and the three things they can do
- Dimensional formulae worth knowing cold
- What dimensional analysis cannot do
- Traps that cost marks
- Tricks that save time
How CapCompass uses this sheet
These notes are not a standalone PDF. CapCompass plans Physics chapter by chapter against your real exam dates and free hours, and when the plan reaches Physical World and Measurement the sheet opens inside the study block itself — at the page covering the sub-topic that block is on, with the timer still running. Revision arrives at the moment the plan says revise, instead of having to be gone looking for.