JEE · Physics · Units, Dimensions & Measurement doubts
8 doubts found
What does “Dimensional analysis” actually mean in Units, Dimensions & Measurement, and why does it matter for JEE?
expressing every quantity in powers of mass (M), length (L) and time (T) so you can check or derive relations.
I keep getting “Dimensional analysis” questions wrong in Units, Dimensions & Measurement. What's the trap?
thinking a dimensionally-correct equation must be numerically correct — dimensionless constants (like 2 or π) are invisible to it.
What does “Significant figures” actually mean in Units, Dimensions & Measurement, and why does it matter for JEE?
the digits in a measurement that actually carry meaning, reflecting the instrument's precision.
I keep getting “Significant figures” questions wrong in Units, Dimensions & Measurement. What's the trap?
keeping more digits in the answer than the least-precise measurement allows.
What does “Errors in measurement” actually mean in Units, Dimensions & Measurement, and why does it matter for JEE?
absolute error = |measured − true|, relative error = absolute/true, percentage error = relative × 100.
I keep getting “Errors in measurement” questions wrong in Units, Dimensions & Measurement. What's the trap?
mixing up accuracy (closeness to the true value) with precision (repeatability).
What does “Least count” actually mean in Units, Dimensions & Measurement, and why does it matter for JEE?
the smallest value an instrument can reliably read — e.g. 0.01 mm for a screw gauge.
I keep getting “Least count” questions wrong in Units, Dimensions & Measurement. What's the trap?
forgetting the zero-error correction of a vernier or screw gauge.