Accuracy, Precision, and Resolution
Accuracy is agreement between a measured result and an accepted reference, precision is agreement among repeated results under stated conditions, and resolution or least count is the smallest indicated increment of the measuring system.
Why this shows up in the exam
Choosing instruments · Assessing repeated trials · Interpreting calibration reports
Learn the idea
Accuracy concerns closeness to a reference, precision concerns repeatability, and resolution is the smallest detectable change. A tight cluster can miss the target and a wide cluster can average near it; instrument resolution is a separate limit on what changes can be displayed.
🧠 Memory hook: Target, cluster, tick: accuracy, precision, resolution.
Get this one clearly and it pays off every single time it shows up in the paper. 🎯
Formulas & facts to keep ready
- error = measured value - reference value — signed measurement error when a reference exists
- resolution = smallest distinguishable indication — instrument display or scale limit
How to approach it
- 1Identify the reference and repeats
- 2Separate bias from spread
- 3Report only resolution-supported digits
Common slip-ups that cost marks
- •Using accuracy and precision as synonyms
- •Claiming extra digits beyond resolution
- •Calling a single reading precise without repeatability evidence
🌟 That's the whole idea — you've got this. Try the practice set below; every question you attempt makes it stick a little harder.
Original chapter practice
Original questions for this chapter, not past-paper questions or an exact mapping to this individual concept.
A quantity Q is defined as Q = force^1 / speed^2. Which dimensional formula represents Q?
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