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Demystifying Measurement & Error Concepts: A 40-MCQ Challenge for Physics Learners

Understanding measurements, significant figures, units, dimensional formulas, and types of errors is one of the most essential foundations in physics. Whether you’re preparing for competitive exams or building clarity for school-level physics, mastering these concepts strengthens your analytical skills and boosts your accuracy in problem-solving.

This guide covers every major concept—absolute error, relative error, percentage error, precision, accuracy, vernier calipers, screw gauge calculations, dimensional analysis, consistency of equations, and more. After the explanation, you’ll find 40 carefully selected MCQs with options and correct answers.

Table of Contents

40 MCQs on Significant Figures, Errors & Dimensional Analysis (With Answers)

1. The number of significant figures in 0.06900 is:

a) 5 b) 4 c) 2 d) 3
Answer: b

2. If separation between screen and point source is increased by 2%, intensity will:

a) Increase by 4% b) Increase by 2% c) Decrease by 2% d) Decrease by 4%
Answer: d

3. Average absolute error of times: 2.63, 2.56, 2.42, 2.71, 2.80

a) 0.1 s b) 0.11 s c) 0.01 s d) 1.0 s
Answer: b

4. For R = V/i, V = 100 ± 5, i = 10 ± 0.2. Total error in R is:

a) 5% b) 7% c) 5.2% d) 5/2%
Answer: b

5. Length of a cylindrical wire increased by 100%. Change in resistance is:

a) 200% b) 100% c) 50% d) 300%
Answer: d

6. Incorrect statement is:

a) Every measurement has some error
b) Every calculated physical quantity has error
c) Accuracy can be high but precision low
d) Percentage error is different from relative error
Answer: d

7. Error in calorimeter method arises due to:

a) Absence of heat loss cover
b) No water equivalent
c) Both (a) and (b)
d) None
Answer: c

8. Ten vernier divisions = nine main scale divisions (½ mm). Vernier constant is:

a) 0.005 mm b) 0.05 mm c) 0.5 mm d) 0.1 mm
Answer: b

9. Least count of slide caliper: n vernier = (n–1) MS divisions

a) 1/n MSD b) 1/(n−1) MSD c) n/(n−1) MSD d) (n−1)/n MSD
Answer: a

10. Accuracy increases by:

a) Less trials b) More trials c) Significant digits d) Order of magnitude
Answer: b

11. Potential difference with significant figures (10.932 Ω, 4.25 A):

a) 46.461 V b) 46.46 V c) 46.4 V d) 46.0 V
Answer: d

12. Significant figures in 6.25 × 10³

a) 1 b) 6 c) 4 d) 3
Answer: d

13. If force, acceleration, time are fundamental units, dimensional formula of energy:

a) FA²T b) FAT² c) F²AT d) FAT
Answer: b

14. Frequency dependence on ρ, a, T:

a) k √T / (ρ¹/² a³/²) b) k ρ³/² a³/² √T
c) k ρ¹/² a³/² / T³/² d) None
Answer: a

15. Dimensions of GIM²/E² same as:

a) Time b) Mass c) Length d) Force
Answer: a

16. CGS → MKS conversion factor for Young’s modulus:

a) 1 b) 10 c) 0.1 d) 0.01
Answer: c

17. EL² / MG² has dimensions of:

a) Length b) Mass c) Time d) Angle
Answer: d

18. Dimensions of “a” in (P + a/v²)(V – b) = RT:

a) [L³] b) [ML³T⁻²] c) [ML⁵T⁻²] d) [ML²]
Answer: c

19. If x = at + bt² (x in km, t in s), units of b are:

a) km/s b) km·s c) km/s² d) km·s²
Answer: c

20. Dimensions of a, b, c in v = at + b/(t + c):

a) a = L², b = T, c = LT²
b) a = LT², b = LT, c = L
c) a = LT⁻², b = L, c = T
d) a = L, b = LT, c = T²
Answer: c

21. Universal time is based on:

a) Earth rotation b) Earth revolution c) Cesium atom vibration d) Quartz oscillation
Answer: c

22. Unit of absolute permittivity:

a) F·m b) F/m c) F/m² d) F
Answer: b

23. Dimensions of 1/√(μ₀ε₀) are similar to:

a) Distance b) Velocity c) Acceleration d) None
Answer: b

24. Same dimensions pair:

a) Pressure & stress b) Stress & strain
c) Pressure & force d) Power & force
Answer: a

25. ‘rad’ is unit of:

a) Ionising ability
b) Energy delivered
c) Biological effect
d) Rate of decay
Answer: c

26. Water equivalent is expressed in:

a) Calorie b) Gram c) Kelvin d) Erg
Answer: b

27. Unit of nuclear dose:

a) Fermi b) Curie c) Rutherford d) Roentgen
Answer: d

28. Parallactic second is unit of:

a) Time b) Velocity c) Distance d) Angle
Answer: c

29. Dimensions of (angular momentum / linear momentum):

a) M L⁻³ b) L⁻¹ T⁻²
c) T⁻¹ d) L
Answer: d

30. Dimensions of specific gravity:

a) M L⁻³ b) L T⁻²
c) T⁻¹ d) Dimensionless
Answer: d

31. Units doubled → unit of angular momentum becomes:

a) Doubled b) Tripled c) Quadrupled d) 8×
Answer: c

32. Same in all inertial frames:

a) Force b) Velocity c) Displacement d) Kinetic energy
Answer: d

33. Incorrectly expressed unit:

a) Torque: N·m
b) Stress: N/m²
c) Modulus: N/m²
d) Surface tension: N/m⁻²
Answer: d

34. Same dimensions:

a) Frequency, angular frequency, angular momentum
b) Acceleration, momentum, retardation
c) Thermal capacity, specific heat, entropy
d) Work, energy, torque
Answer: d

35. Equal dimensions:

a) Torque & work b) Stress & energy
c) Force & stress d) Force & work
Answer: a

36. Dimensional analysis cannot be used for:

a) Deriving relations
b) Fourth unknown variable
c) Converting units
d) Checking correctness
Answer: b

37. Ampere-hour is unit of:

a) Quantity of electricity b) Current
c) Power d) Energy
Answer: a

38. Derived quantity is:

a) Temperature b) Ampere c) Candela d) Lumen
Answer: d

39. Dimensionally correct equation:

a) Pressure = Force/volume
b) Pressure = Momentum/(volume·time)
c) Pressure = Energy/volume
d) Pressure = Energy/(volume·time)
Answer: c

40. Same dimensions:

a) Pressure & stress b) Pressure & force
c) Stress & strain d) Power & force
Answer: a

Conclusion

Mastering measurement, significant figures, dimensional analysis, and error calculation strengthens your foundation for all advanced topics in physics. These 40 MCQs cover the most frequently tested concepts—helping you improve not only accuracy but also conceptual clarity. Whether you’re preparing for NEET, JEE, board exams, or competitive assessments, understanding the logic behind measurements and units is crucial.

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