9th Physics Chapter # 1- (physical quantities and measurements) - Important Shorts - (New Book 2026)

📌 Topics for Short Questions – Chapter 1 (Physical Quantities and Measurements)

Short questions in board exams usually come from these topics:


 
 
#Short QuestionKey Point
1What is a physical quantity?A quantity that can be measured
2What is a non-physical quantity?A quantity that cannot be measured
3What are base quantities?Seven fundamental quantities
4What are derived quantities?Quantities derived from base quantities
5Name the seven base quantities.Length, mass, time, current, temp, mole, luminous intensity
6What is the SI unit of length?Meter (m)
7What is the SI unit of mass?Kilogram (kg)
8What is the SI unit of time?Second (s)
9What is the SI unit of temperature?Kelvin (K)
10What is the SI unit of electric current?Ampere (A)
11What is the SI unit of amount of substance?Mole (mol)
12What is the SI unit of luminous intensity?Candela (cd)
13What is the least count of a ruler?1 mm or 0.1 cm
14What is the least count of vernier callipers?0.01 cm or 0.1 mm
15What is the least count of micrometer screw gauge?0.001 cm or 0.01 mm
16Define least count.Smallest value that can be measured
17What is zero error?Reading when instrument measures nothing
18What is positive zero error?Positive reading when measuring nothing
19What is negative zero error?Negative reading when measuring nothing
20Define scientific notation.Writing numbers as a × 10ⁿ
21What are SI prefixes?Prefixes added before units
22What is the prefix for 10³?Kilo (k)
23What is the prefix for 10⁻³?Milli (m)
24What is the prefix for 10⁻⁶?Micro (μ)
25What is the prefix for 10⁹?Giga (G)
26What is the prefix for 10⁶?Mega (M)
27What is the prefix for 10⁻⁹?Nano (n)
28Define significant figures.Digits that carry meaningful information
29How many significant figures are in 2.5?2 SF
30How many significant figures are in 0.025?2 SF
31How many significant figures are in 2500?2 SF
32Define precision.Closeness of repeated measurements
33Define accuracy.Closeness to true value
34What is a measuring cylinder used for?Measuring volume of liquids
35What is the displacement can method?For measuring volume of irregular objects
36What is human error?Error due to observer’s mistake
37What is systematic error?Consistent error in one direction
38What is random error?Error that occurs randomly
39Define uncertainty.Doubt or lack of precision
40What is the principle of physical balance?Works on equal arms principle
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Notes