JEE · NEET · AIIMS · BITSAT · KVPY
📏 Master Units & Measurements
NCERT Class 11 · Chapter 1
Real PYQs from top competitive exams — filter by exam, attempt each question, track your progress and submit to see your full score report.
50
Real PYQs
5
Exam Bodies
15+
Years Covered
~6%
Exam Weightage
PYQs Overview
Dimensional Analysis
Deriving formulae, checking homogeneity, converting units — most-tested numerical.
★★★★★
93% Frequency
Error Analysis
Absolute, relative, percentage error; error in sum, product, power.
★★★★★
88% Frequency
Significant Figures & Rounding
Rules for counting sig figs; arithmetic with sig figs.
★★★★☆
76% Frequency
SI Units & Supplementary Units
7 base quantities, SI units, supplementary (radian, steradian).
★★★★☆
82% Frequency
Vernier Callipers & Screw Gauge
Least count, zero error, reading measurements — numerical.
★★★★☆
70% Frequency
Order of Magnitude
Estimations, powers of 10, size comparison of physical quantities.
★★★☆☆
55% Frequency
Topic Frequency
💡 Did You Know?
- Dimensional analysis asked in every JEE paper
- Error propagation numerical — 8× in JEE since 2010
- SI base units = 7 (kg, m, s, A, K, mol, cd)
- Zero error in Vernier — asked every NEET year
- Numericals = ~70% of chapter marks
Key Takeaways
7 base SI units — memorise all
kg, m, s, A, K, mol, cd. Supplementary: rad, sr.
Dimensional formula of every physical quantity
[M^a L^b T^c] — derive for force, energy, pressure, viscosity etc.
Error in product/quotient: add relative errors
ΔZ/Z = ΔA/A + ΔB/B. For power n: ΔZ/Z = n·ΔA/A.
Least count = 1 MSD – 1 VSD
For Vernier: LC = 1 MSD/n. For screw gauge: LC = pitch/n.
Significant figures rules — 3 key cases
Leading zeros: not significant. Trailing zeros after decimal: significant.
Homogeneity principle: dimensions must match
Use to check formula correctness and derive missing constants.
Study Strategy
1
SI Units & DimensionsDay 1–2
All 7 base units + dimensional formulae for 30+ quantities.
2
Dimensional AnalysisDay 3
Checking, deriving, converting — 20 practice problems.
3
Error AnalysisDay 4
Sum, product, quotient, power rules — 15 numerical problems.
4
InstrumentsDay 5
Vernier callipers, screw gauge — LC, zero error, readings.
5
Significant FiguresDay 6
Rules + arithmetic. 15 practice sums.
6
Attempt All PYQsDay 7
Focus on dimensional analysis and error MCQs.
7
Mock TestDay 8
Timed 30-Q mock. Dimensional analysis = highest priority.
🗓️ 8-Day Chapter Plan
| Day 1–2 | SI Units & Dimensions |
| Day 3 | Dimensional Analysis |
| Day 4 | Error Analysis |
| Day 5 | Instruments |
| Day 6 | Significant Figures |
| Day 7 | Attempt All PYQs |
| Day 8 | Mock Test |
🧠 Pro Tip: Dimensional analysis alone is worth 3–4 marks in JEE. Master deriving unknowns from given quantities.
🚀
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Units & Measurements question?
Real PYQs, topic-wise overview, key takeaways and an 8-day strategy — all in one place.
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