Units and Measurements — Class 11 CBSE Physics revision notes
A 6-page visual revision sheet for Units and Measurements, written for Class 11 CBSE 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
Units and Measurements in one look
seven units, honest digits, and how wrong you're allowed to be
The seven base units
- Length: metre (m)
- Mass: kilogram (kg)
- Time: second (s)
- Electric current: ampere (A)
- Temperature: kelvin (K)
- Amount of substance: mole (mol)
- Luminous intensity: candela (cd)
A physical quantity
- a physical quantity = a number × a unit: without its unit the number means nothing
- change the unit and the number changes the other way: n_1u_1 = n_2u_2
- base quantities have units of their own; every other unit is built from them (derived)
Prefixes
- a prefix is a power of ten stuck to the unit: km, ms, µs, nm
- shift the decimal by counting the power of ten, don't hunt for a conversion factor
A sense of scale, order of magnitude
- order of magnitude: the power n when written A × 10^n, 0.5 ≤ A < 5
Page 1 of 6. The full sheet, all 6 pages, opens free in the app.
What this Units and Measurements sheet covers
- The seven base units
- Length
- Mass
- Time
- Electric current
- Temperature
- Amount of substance
- Luminous intensity
- A physical quantity
- Prefixes
- A sense of scale, order of magnitude
- Supplementary & derived units
- Significant figures, counting rules
- Significant figures in calculations
- Dimensions of common quantities
- Principle of homogeneity
- Three jobs dimensional analysis does
- Where it fails
- Accuracy vs precision
- Accuracy
- Precision
- Errors, defined
- absolute error, one reading
- mean absolute error
- relative error; × 100\% for the percentage error
- Combining errors
- sum or difference, Z = A ± B
- product or quotient, Z = AB or A/B
- a power, Z = A^pB^q/C^r
- Products and powers
- Vernier callipers
- 10 VSD = 9 MSD: 0.1 mm; 20 VSD = 19 MSD: 0.05 mm
- main scale, then the line that coincides
- Least count
- Screw gauge
- least count: the pitch (one full turn) shared among the circular divisions
- reading: pitch-scale reading, then the circular division on the index line times LC
- In the lab: the spherometer
- 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 Units and Measurements 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.