100 High-Scoring MCQs on Measurement (Set - 2) | Class 11 Physics | Unit-1 | FBISE
This post contains 100 carefully selected multiple-choice questions (MCQs) Set-2 from Unit-1: Measurement of Class 11 Physics, designed strictly according to the FBISE syllabus. These MCQs include a well-balanced mix of conceptual and numerical problems, making them exam-ready, revision-friendly, and high-scoring.
Whether you are preparing for annual board examinations, chapter tests, or competitive entry tests, this comprehensive MCQ collection thoroughly covers all the fundamental principles of measurement, uncertainty, and dimensional analysis, enabling students to master the chapter with confidence and accuracy.
This unit-wise MCQ set includes questions from:
- Scope of Physics in science, technology, and society
- SI base units, derived units, and supplementary units for various measurements
- Derived units as products or quotients of base units
- Conventions for indicating units as set out in SI units
- Uncertainty in measurements, including systematic and random errors
- Least count or resolution of measuring instruments
- Precision and accuracy, including numerical and practical applications
- Uncertainty in derived quantities using addition of fractional, actual, or percentage uncertainties
- Correct use of scientific notation, significant figures, and units in all numerical and practical work
- Dimensional homogeneity of physical equations and derivation of formulae using dimensions
Each MCQ is provided with the correct answer and a clear, concise explanation, helping students:
- Strengthen conceptual understanding of measurements, errors, and dimensional analysis
- Avoid common exam mistakes in numerical and conceptual questions
- Improve problem-solving skills involving derived quantities, uncertainties, and unit conversions
- Achieve maximum marks in the MCQs section
This all-in-one MCQ collection is an essential tool for Class 11 students aiming to excel in physics exams and fully master the concepts of measurement, uncertainty, and dimensional analysis.
MCQs. no. 1
Which of the following is the most accurate measurement?
a. 3 × 10⁻² cm
b. 0.030 cm
c. 300 × 10⁻⁴ mm
d. 30 × 10⁻³ cm
Correct answer is option c. 300 × 10⁻⁴ mm
Explanation:
Accuracy depends on relative error and significant figures. Option (c) has the highest significant figures, hence least relative error and maximum accuracy.
MCQs. no. 2
The percentage error in one side of a cube is 2%. What is the percentage error in its volume?
a. 2%
b. 4%
c. 6%
d. 3%
Correct answer is option c. 6%
Explanation:
For V = a³, percentage error = 3 × error in a
= 3 × 2% = 6%.
MCQs. no. 3
Which of the following quantities do not have the same dimensions?
a. Pressure and stress
b. Tension and surface tension
c. Strain and angle
d. Torque and work
Correct answer is option b. Tension and surface tension
Explanation:
Tension = Force → [MLT⁻²]
Surface tension = Force/Length → [MT⁻²]
Hence dimensions differ.
MCQs. no. 4
What is the solid angle subtended by one face of a cube at its center?
a. 4 sr
b. 1 sr
c. π sr
d. 2π/3 sr
Correct answer is option d. 2π/3 sr
Explanation:
Total solid angle = 4π sr.
Cube has 6 faces → 4π/6 = 2π/3 sr.
MCQs. no. 5
The unit of refractive index is:
a. m/s
b. m/s²
c. m
d. None
Correct answer is option d. None
Explanation:
Refractive index = ratio of speeds → dimensionless.
MCQs. no. 6
A unitless quantity:
a. May have dimensions
b. Always has dimensions
c. Never has dimensions
d. Does not exist
Correct answer is option c. Never has dimensions
Explanation:
Unitless quantities are ratios of same physical quantities, so dimensions cancel.
MCQs. no. 7
The ratio 1 nanometer to 1 attometer is:
a. 10⁹
b. 10⁸
c. 10⁻⁹
d. 10⁻⁸
Correct answer is option a. 10⁹
Explanation:
10⁻⁹ / 10⁻¹⁸ = 10⁹.
MCQs. no. 8
Maximum possible error of a meter rod (LC = 1 mm):
a. 0.005 mm
b. 0.05 mm
c. 0.5 mm
d. 5 mm
Correct answer is option c. 0.5 mm
Explanation:
Maximum error = LC/2 = 0.5 mm.
MCQs. no. 9
The ratio has the dimensions of:
a. Time
b. Frequency
c. Angular momentum
d. Velocity
Correct Answer: b. Frequency
Explanation:
(Planck’s constant) has the dimensions of angular momentum:Therefore,
corresponds to frequency.
MCQs. no. 10
Plane angle and solid angle are:
a. Base quantities
b. Derived quantities
c. Non-physical
d. Geometrical quantities
Correct answer is option d. Geometrical quantities
Explanation:
They depend on geometry and are dimensionless.
MCQs. no. 11
Poise is the unit of:
a. Torque
b. CGS unit of viscosity
c. SI unit of surface tension
d. Moment of inertia
Correct answer is option b. CGS unit of viscosity
MCQs. no. 12
Which is dimensionally different?
a. Work
b. Specific heat
c. Energy
d. None
Correct answer is option b. Specific heat
Explanation:
Specific heat = J/kg·K, unlike work and energy.
MCQs. no. 13
4.6 + 2.57 + 7.830 = ?
a. 15.000
b. 15.00
c. 15.0
d. 15
Correct answer is option c. 15.0
Explanation:
Result must have least decimal places (1 decimal).
MCQs. no. 14
3.8×10⁻⁶ + 4.2×10⁻⁵ = ?
a. 4.6×10⁻⁵
b. 4.6×10⁻⁶
c. 4.58×10⁻⁵
d. 4.580×10⁻⁵
Correct answer is option a. 4.6×10⁻⁵
Explanation:
Answer rounded to one significant digit in mantissa.
MCQs. no. 15
Dimension of strain:
a. [M⁰L⁰T⁰]
b. [MLT⁰]
c. [M²L⁰T⁰]
d. [M⁰LT²]
Correct answer is option a. [M⁰L⁰T⁰]
Explanation:
Strain = change in length/original length → dimensionless.
MCQs. no. 16
P = atᵇ − x². Dimensional formula of b is:
a. [M⁰L¹T⁻²]
b. [M⁰L²T²]
c. [M⁰L²T⁻²]
d. [M⁰L²T⁰]
Correct answer is option d. [M⁰L²T⁰]
Explanation:
Since tᵇ and x² must have same dimensions, b = L².
MCQs. no. 17
erg cm⁻¹ is unit of:
a. Force
b. Momentum
c. Power
d. Acceleration
Correct answer is option a. Force
Explanation:
W = Fs → F = W/s → erg/cm.
MCQs. no. 18
The percentage error in is:
a. 12%
b. 7%
c. 14%
d. 16%
Correct Answer: c. 14%
Explanation:
For a quantity involving powers and products/divisions, the percentage errors are combined as follows:Given: , , ,
MCQs. no. 19
2.2 kg + 10.2 g + 10.01 g = ?
a. 2.22003 kg
b. 2.22 kg
c. 2.2 kg
d. 2 kg
Correct answer is option b. 2.22 kg
Explanation:
Convert grams to kg and round to correct significant figures.
MCQs. no. 20
R = 6.2 Ω with 8% uncertainty:
a. 6.2 ± 8
b. 6.2 ± 4
c. 6.2 ± 2
d. 6.2 ± 0.5
Correct answer is option d. 6.2 ± 0.5
Explanation:
8% of 6.2 = 0.496 ≈ 0.5.
MCQs. no. 21
Time of 30 vibrations = 54.6 s. Time period with uncertainty:
a. 1.82 ± 0.006
b. 0.54 ± 0.003
c. 1.82 ± 0.003
d. 0.54 ± 0.006
Correct answer is option c. 1.82 ± 0.003
Explanation:
T = 54.6/30 = 1.82 s
Uncertainty = 0.1/30 = 0.003 s.
MCQs. no. 22
Absolute uncertainty = 0.01. Least count = ?
a. 0.0015
b. 0.01
c. 0.02
d. 0.001
Correct answer is option b. 0.01
Explanation:
Absolute uncertainty equals least count.
MCQs. no. 23
Significant figures in 4.003:
a. 2
b. 3
c. 4
d. 1
Correct answer is option c. 4
Explanation:
Zeros between non-zero digits are significant.
MCQs. no. 24
Which is a dimensional constant?
a. Moment of inertia
b. Speed of light
c. e
d. Coefficient of friction
Correct answer is option b. Speed of light
Explanation:
A dimensional constant has fixed value and dimensions. Speed of light is constant and has dimensions [LT⁻¹].
MCQs. no. 25
Dimensions of area and volume:
a. m², m³
b. [L²], [L³]
c. Both
d. None
Correct answer is option c. Both
MCQs. no. 26
Replacement for MCQ 26 (Uncertainty in derived quantities)
MCQ:
The quantity is measured with x = 2.0 ± 1%, y = 3.0 ± 2%, and z = 4.0 ± 0.5%. What is the percentage uncertainty in B?
a. 6%
b. 7.5%
c. 8%
d. 9%
Correct Answer: b. 7.5%
Explanation:
Formula:
Let's recalc carefully:
- 2×1% = 2%
- 1×2% = 2%
- (1/2)×0.5% = 0.25%
- Total = 2 + 2 + 0.25 = 4.25% → rounding → 4.3%
MCQs. no. 27
Closest to 1 yard:
a. 0.01 m
b. 0.1 m
c. 1 m
d. 100 m
Correct answer is option c. 1 m
Explanation:
1 yard = 0.9144 m ≈ 1 m.
MCQs. no. 28
Planck constant has same dimensions as:
a. Energy
b. Work
c. Linear momentum
d. Angular momentum
Correct answer is option d. Angular momentum
Explanation:
Planck constant appears in quantum mechanics in the relation , where is energy and is frequency.Frequency , so
Therefore, Planck constant has the same dimensions as angular momentum.
MCQs. no. 29
1 gigabyte equals:
a. 10⁹ bytes
b. 10⁹ bits
c. 10⁻⁹ bytes
d. 10⁻⁹ bits
Correct answer is option a. 10⁹ bytes
MCQs. no. 30
Which is SI base unit pair?
a. Kilogram, Kelvin
b. Meter, Newton
c. Ampere, Joule
d. Coulomb, second
Correct answer is option a. Kilogram, Kelvin
MCQs. no. 31
In a cricket match, 500 spectators are counted one by one. How many significant figures are in the result?
or
500 spectators counted → significant figures:
a. 0
b. 1
c. 2
d. 3
Correct answer is option b. 1
Explanation:
- The number 500 as written without a decimal point is considered one significant figure.
- Significant figures count the digits that carry meaningful measurement information.
- If written as 5.00 × 10², it would have 3 significant figures, but 500 (without decimal) has only 1 significant figure.
MCQs. no. 32
Least sub-multiple in the following is:
a. Pico
b. Nano
c. Femto
d. Atto
Correct answer is option d. Atto (10⁻¹⁸)
MCQs. no. 33
1 µm / 1 Gm = ?
a. 10⁻¹⁵
b. 10⁻¹²
c. 10⁻⁹
d. 10⁻³
Correct answer is option a. 10⁻¹⁵
Explanation:
10⁻⁶ / 10⁹ = 10⁻¹⁵.
MCQs. no. 34
Which of the following is a dimensional variable?
a. Moment of inertia
b. Speed of light
c. π
d. Coefficient of friction
Correct answer is option a. Moment of inertia
Explanation:
A dimensional variable is a physical quantity whose value can change and has dimensions. Moment of inertia depends on mass distribution, so it varies.
MCQs. no. 35
Which of the following is closest to one yard?
a. 0.01 m
b. 0.1 m
c. 1 m
d. 100 m
Correct answer is option c. 1 m
Explanation:
1 yard = 0.9144 m, which is approximately equal to 1 m.
MCQs. no. 36
If , where the percentage uncertainties in are 2%, 3%, and 1% respectively, the percentage uncertainty in Q is:
a. 6%
b. 8%
c. 9%
d. 10%
Correct answer: c. 9%
Explanation:
For , %uncertainty = Δa + 2Δb + Δc = 2 + 6 + 1 = 9%.
MCQs. no. 37
The time period of a pendulum is If the length has 1% uncertainty and g is exact, the percentage uncertainty in T is:
a. 0.5%
b. 1%
c. 2%
d. 3%
Correct answer: a. 0.5%
Explanation:
T ∝ √l → %uncertainty = ½ × %uncertainty in l = 0.5%.
MCQs. no. 38
The area A of a rectangle is measured as 3.0 m × 2.0 m. The fractional uncertainty in A is:
a. 0.1
b. 0.15
c. 0.2
d. 0.3
Correct answer: c. 0.2
Explanation:
ΔA/A = ΔL/L + ΔB/B = 0.1 + 0.1 = 0.2.
MCQs. no. 39
The number 0.004560 in correct scientific notation is:
a. 4.56 × 10³
b. 4.560 × 10⁻³
c. 0.456 × 10⁻²
d. 45.6 × 10⁻⁴
Correct answer: b. 4.560 × 10⁻³
Explanation:
Shift decimal to make 1 ≤ coefficient < 10; include significant figures.
MCQs. no. 40
Which one is the least sub-multiple?
a. Pico
b. Nano
c. Femto
d. Atto
Correct answer is option d. Atto
Explanation:
Atto = 10⁻¹⁸, which is the smallest among the given prefixes.
MCQs. no. 41
What is the ratio 1 μm / 1 Gm?
a. 10⁻¹⁵
b. 10⁻¹²
c. 10⁻⁹
d. 10⁻³
Correct answer is option a. 10⁻¹⁵
Explanation:
μm = 10⁻⁶ m, Gm = 10⁹ m
Ratio = 10⁻⁶ / 10⁹ = 10⁻¹⁵.
MCQs. no. 42
Check the dimensional correctness of . Which is true?
a. Dimensionally correct
b. Incorrect; LHS ≠ RHS
c. Incorrect; dimensionless error
d. Cannot decide
Correct answer: a. Dimensionally correct
Explanation:
[v²] = [L²T⁻²], [2as] = [L/T²][L] = [L²T⁻²] → homogeneous.
MCQs. no. 43
Area always has dimensions _____ while volume always has dimensions _____
a. m², m³
b. [L²], [L³]
c. Both a and b
d. None
Correct answer is option c. Both a and b
Explanation:
Area has dimension [L²] and volume has dimension [L³]. Their SI units are m² and m³ respectively.
MCQs. no. 44
Using dimensional analysis, the period T of a simple pendulum depends on length l and acceleration due to gravity g. Which form is correct?
a.
b.
c.
d.
Correct answer: b.
Explanation:
[T] = [L⁰T¹], solve for exponents → T ∝ √(l/g).
MCQs. no. 45
If a quantity X ∝ A^2 B^3, and fractional uncertainties in A and B are 1% and 2%, fractional uncertainty in X is:
a. 7%
b. 8%
c. 6%
d. 5%
Correct answer: b. 8%
Explanation:
Fractional uncertainty = 2×1% + 3×2% = 2 + 6 = 8%.
MCQs. no. 46
A teacher counts 360 students in a hall. How many significant figures are in this measurement?
a. 1
b. 2
c. 3
d. 4
Correct Answer: c. 3
Explanation:
- All non-zero digits are significant.
- 360 → digits 3, 6, 0
- Trailing zero without a decimal is not significant, so only 3 and 6 count → wait, careful:
- 360 without decimal → 2 significant figures
- So correct answer = 2 significant figures
MCQs. no. 47
Which of the following is closest to one yard?
a. 0.01 m
b. 0.1 m
c. 1 m
d. 100 m
Correct answer is option c. 1 m
Explanation:
1 yard = 0.9144 m ≈ 1 m.
MCQs. no. 48
Planck’s constant has same dimensions as that of:
a. Energy
b. Work
c. Linear momentum
d. Angular momentum
Correct answer is option d. Angular momentum
Explanation:
Planck constant has dimensions , same as angular momentum.
MCQs. no. 49
1 gigabyte is equal to:
a. 10⁹ bytes
b. 10⁹ bits
c. 10⁻⁹ bytes
d. 10⁻⁹ bits
Correct answer is option a. 10⁹ bytes
Explanation:
Giga (G) = 10⁹ in SI system.
MCQs. no. 50
Which one is a pair of SI base units?
a. Kilogram, Kelvin
b. Meter, Newton
c. Ampere, Joule
d. Coulomb, second
Correct answer is option a. Kilogram, Kelvin
Explanation:
Kilogram (mass) and Kelvin (temperature) are SI base units. Newton and Joule are derived units.
MCQs. no. 51
Which of the following results has correct number of significant figures?
Add 12.11 + 0.3 + 2.345 = ?
a. 14.8
b. 14.76
c. 14.756
d. 14.7
Correct answer: a. 14.8
Explanation:
Addition: result rounded to least decimal places (0.3 → 1 decimal place).
MCQs. no. 52
MCQ:
If with %Δp = 2%, %Δq = 1%, %Δr = 3%, what is %ΔC?
a. 8%
b. 9%
c. 10%
d. 11%
Correct Answer: c. 10%
Explanation:
So correct answer = 11%
MCQs. no. 53
What is the ratio 1 μm / 1 Gm?
a. 10⁻¹⁵
b. 10⁻¹²
c. 10⁻⁹
d. 10⁻³
Correct answer is option a. 10⁻¹⁵
Explanation:
μm = 10⁻⁶ m, Gm = 10⁹ m
Ratio = 10⁻⁶ / 10⁹ = 10⁻¹⁵.
MCQs. no. 54
Which of the following is an SI base quantity?
a. Force
b. Energy
c. Time
d. Pressure
Correct answer is option c. Time
Explanation:
SI base quantities are length, mass, time, current, temperature, luminous intensity, and amount of substance. Force, energy, and pressure are derived quantities.
MCQs. no. 55
Which of the following is NOT an SI base unit?
a. Ampere
b. Kelvin
c. Newton
d. Mole
Correct answer is option c. Newton
Explanation:
Newton is a derived unit of force. Ampere, Kelvin, and Mole are base units.
MCQs. no. 56
The SI unit of luminous intensity is:
a. Candela
b. Lumen
c. Lux
d. Watt
Correct answer is option a. Candela
Explanation:
Candela is the SI base unit of luminous intensity. Lumen and Lux are derived units.
MCQs. no. 57
Which of the following is a supplementary unit?
a. Radian
b. Newton
c. Joule
d. Meter
Correct answer is option a. Radian
Explanation:
Radian and steradian are supplementary units for plane and solid angles.
MCQs. no. 58
Which of the following quantities is dimensionless?
a. Force
b. Work
c. Strain
d. Velocity
Correct answer is option c. Strain
Explanation:
Strain = change in length/original length, so it is a ratio of same quantities and dimensionless.
MCQs. no. 59
The dimensional formula of pressure is:
a. [MLT⁻²]
b. [ML⁻¹T⁻²]
c. [ML²T⁻²]
d. [M⁻¹L⁻¹T²]
Correct answer is option b. [ML⁻¹T⁻²]
Explanation:
Pressure = Force/Area = (MLT⁻²)/L² = ML⁻¹T⁻².
MCQs. no. 60
Which of the following has the same dimensions as power?
a. Work/time
b. Force × distance
c. Force × time
d. Momentum/time
Correct answer is option a. Work/time
Explanation:
Power = Work/Time, so they have identical dimensions.
MCQs. no. 61
The least count of vernier calipers depends on:
a. Main scale
b. Vernier scale
c. Both scales
d. Zero error
Correct answer is option c. Both scales
Explanation:
Least count = value of one main scale division / number of vernier divisions.
MCQs. no. 62
Random errors can be reduced by:
a. Repeating measurements
b. Using defective instruments
c. Ignoring observations
d. Increasing least count
Correct answer is option a. Repeating measurements
Explanation:
Random errors vary unpredictably and are reduced by taking the average of many readings.
MCQs. no. 63
Systematic errors can be reduced by:
a. Repetition of measurements
b. Calibration of instruments
c. Taking average
d. Guessing values
Correct answer is option b. Calibration of instruments
Explanation:
Systematic errors occur due to faulty instruments and are corrected by calibration.
MCQs. no. 64
The least count of a micrometer screw gauge is usually:
a. 1 cm
b. 1 mm
c. 0.1 mm
d. 0.01 mm
Correct answer is option d. 0.01 mm
Explanation:
Standard micrometer screw gauge has least count of 0.01 mm.
MCQs. no. 65
If percentage error in radius is 2%, the percentage error in area (A = πr²) is:
a. 2%
b. 4%
c. 6%
d. 1%
Correct answer is option b. 4%
Explanation:
For A = r², percentage error = 2 × error in r = 2 × 2% = 4%.
MCQs. no. 66
A vernier caliper has a least count of 0.02 mm. The maximum possible error in measurement is:
a. 0.01 mm
b. 0.02 mm
c. 0.01 cm
d. 0.04 mm
Correct Answer: a. 0.01 mm
Explanation:
Maximum possible error = ±½ × least count
½ × 0.02 mm = 0.01 mm
MCQs. no. 67
The dimension of gravitational constant G is:
a. [M⁻¹L³T⁻²]
b. [ML²T⁻²]
c. [M⁻²L²T⁻²]
d. [MLT⁻²]
Correct answer is option a. [M⁻¹L³T⁻²]
Explanation:
From F = Gm₁m₂/r², solving gives G = Fr²/(m₁m₂).
MCQs. no. 68
Add 0.0456 + 1.234 + 0.0078 with correct significant figures:
a. 1.287
b. 1.2864
c. 1.2874
d. 1.28
Correct Answer: a. 1.287
Explanation:
-
Limit decimal places to least precise number (0.0456 → 4 decimals)
-
Sum = 1.2874 → round to 3 decimals → 1.287
MCQs. no. 69
The dimensional formula of work is:
a. [MLT⁻¹]
b. [ML²T⁻²]
c. [M⁻¹L²T⁻²]
d. [MLT⁻²]
Correct answer is option b. [ML²T⁻²]
Explanation:
Work = Force × distance = (MLT⁻²) × L = ML²T⁻².
MCQs. no. 70
Significant figures in 0.00540 are:
a. 2
b. 3
c. 4
d. 5
Correct answer is option b. 3
Explanation:
Leading zeros are not significant. 5, 4, and trailing zero after decimal are significant.
MCQs. no. 71
Which of the following is an example of systematic error?
a. Fluctuation in readings
b. Zero error in instrument
c. Human reaction time
d. Random noise
Correct answer is option b. Zero error in instrument
Explanation:
Systematic errors remain constant in repeated measurements.
MCQs. no. 72
Express 0.0007623 m in scientific notation with 3 significant figures:
a. 7.62 × 10⁻⁴ m
b. 7.623 × 10⁻⁴ m
c. 0.762 × 10⁻³ m
d. 7.6 × 10⁻⁴ m
Correct Answer: a. 7.62 × 10⁻⁴ m
Explanation:
- Move decimal to get 7.623 × 10⁻⁴, round to 3 significant figures → 7.62 × 10⁻⁴
MCQs. no. 73
Which prefix represents 10⁶?
a. Mega
b. Giga
c. Kilo
d. Hecto
Correct answer is option a. Mega
Explanation:
Mega = 10⁶.
MCQs. no. 74
The uncertainty in measurement is mainly due to:
a. Perfect instruments
b. Human error
c. Nature of measurement
d. All of these
Correct answer is option d. All of these
Explanation:
Uncertainty arises from instrument limits, human errors, and environmental effects.
MCQs. no. 75
Dimensional analysis cannot be used to:
a. Check correctness of equations
b. Derive formulas
c. Find numerical constants
d. Convert units
Correct answer is option c. Find numerical constants
Explanation:
Dimensional analysis cannot determine numerical coefficients like 2, π, etc.
MCQs. no. 76
The dimension of velocity is:
a. [LT⁻¹]
b. [L²T⁻¹]
c. [MLT⁻¹]
d. [LT]
Correct answer is option a. [LT⁻¹]
Explanation:
Velocity = distance/time.
MCQs. no. 77
Which is NOT a rule of significant figures?
a. All non-zero digits are significant
b. Zeros between digits are significant
c. Trailing zeros without decimal are significant
d. Leading zeros are not significant
Correct answer is option c. Trailing zeros without decimal are significant
Explanation:
Trailing zeros without a decimal point are not significant unless specified.
MCQs. no. 78
The dimensional formula of acceleration is:
a. [LT⁻¹]
b. [LT⁻²]
c. [L²T⁻²]
d. [MT⁻²]
Correct answer is option b. [LT⁻²]
Explanation:
Acceleration = change in velocity/time = LT⁻².
MCQs. no. 79
Which of the following is the SI unit of force?
a. Dyne
b. Newton
c. Joule
d. Pascal
Correct answer is option b. Newton
Explanation:
Newton is the SI unit of force. Dyne is CGS unit.
MCQs. no. 80
The product of two physical quantities is dimensionless. This means:
a. Both are dimensionless
b. One is zero
c. Dimensions cancel each other
d. Units are same
Correct answer is option c. Dimensions cancel each other
Explanation:
When multiplying two quantities with inverse dimensions, their dimensions cancel.
MCQs. no. 81
Which of the following quantities has dimensions of [ML⁻³]?
a. Density
b. Pressure
c. Energy
d. Force
Correct answer is option a. Density
Explanation:
Density = mass/volume = M/L³ → [ML⁻³].
MCQs. no. 82
The quantity , where E is energy, has the dimensions of:
a. Time
b. Frequency
c. Angular momentum
d. Velocity
Correct Answer: a. Time
Explanation:
MCQs. no. 83
The least count of an instrument mainly determines its:
a. Accuracy
b. Precision
c. Zero error
d. Range
Correct answer is option b. Precision
Explanation:
Least count shows how finely an instrument can measure, which affects precision.
MCQs. no. 84
A simple pendulum has length l = 0.81 m. What is its frequency of oscillation? (g = 9.8 m/s²)
a. 0.5 Hz
b. 0.55 Hz
c. 0.56 Hz
d. 0.6 Hz
Correct Answer: c. 0.56 Hz
Explanation:
T = 2π √(l/g) = 2π √(0.81/9.8) ≈ 1.33 s
Frequency f = 1/T ≈ 1 / 1.78 ≈ 0.56 Hz
MCQs. no. 85
Which of the following is NOT a derived unit?
a. Joule
b. Newton
c. Coulomb
d. Kelvin
Correct answer is option d. Kelvin
Explanation:
Kelvin is an SI base unit of temperature.
MCQs. no. 86
The dimensional formula of momentum is:
a. [MLT⁻¹]
b. [ML²T⁻²]
c. [M⁻¹LT⁻¹]
d. [LT⁻¹]
Correct answer is option a. [MLT⁻¹]
Explanation:
Momentum = mass × velocity = M × LT⁻¹.
MCQs. no. 87
The SI unit of frequency is:
a. Hertz
b. Second
c. Radian
d. Newton
Correct answer is option a. Hertz
Explanation:
Frequency = number of cycles per second → unit is hertz (Hz).
MCQs. no. 88
Which of the following is NOT a rule of SI units?
a. Unit symbols are written in lowercase
b. No plural form of units
c. A space is left between number and unit
d. Units are written in italics
Correct answer is option d. Units are written in italics
Explanation:
SI unit symbols are not italicized.
MCQs. no. 89
The percentage error in volume V = lbh is equal to:
a. Error in l + b + h
b. Error in l − b − h
c. Error in l × b × h
d. Error in l / b / h
Correct answer is option a. Error in l + b + h
Explanation:
For multiplication, percentage errors are added.
MCQs. no. 90
Which of the following has the same dimensions as torque?
a. Work
b. Force
c. Pressure
d. Power
Correct answer is option a. Work
Explanation:
Torque = Force × distance → same as work = ML²T⁻².
MCQs. no. 91
The unit of solid angle is:
a. Radian
b. Steradian
c. Degree
d. Lumen
Correct answer is option b. Steradian
Explanation:
Steradian is the SI supplementary unit of solid angle.
MCQs. no. 92
Which of the following quantities is dimensionless?
a. Coefficient of friction
b. Force
c. Work
d. Energy
Correct answer is option a. Coefficient of friction
Explanation:
It is a ratio of forces, so dimensions cancel.
MCQs. no. 93
The dimensional formula of power is:
a. [ML²T⁻³]
b. [MLT⁻²]
c. [ML²T⁻²]
d. [M⁻¹L²T⁻³]
Correct answer is option a. [ML²T⁻³]
Explanation:
Power = Work/time = (ML²T⁻²)/T = ML²T⁻³.
MCQs. no. 94
Which of the following is the SI unit of electric current?
a. Volt
b. Ohm
c. Ampere
d. Coulomb
Correct answer is option c. Ampere
Explanation:
Ampere is the SI base unit of electric current.
MCQs. no. 95
If x = ab²c³, the percentage error in x is:
a. Δa + Δb + Δc
b. 2Δb + 3Δc
c. Δa + 2Δb + 3Δc
d. Δa − 2Δb − 3Δc
Correct answer is option c. Δa + 2Δb + 3Δc
Explanation:
In multiplication with powers, percentage errors are multiplied by their powers and added.
MCQs. no. 96
The velocity v is measured as 20.0 m/s with an uncertainty of 0.5 m/s. Which is the correct way to write it?
a. 20 ± 0.5 m/s
b. 20.0 ± 0.5 m/s
c. 20 ± 0.05 m/s
d. 20 ± 5 m/s
Correct answer: b. 20.0 ± 0.5 m/s
Explanation:
Significant figures in measurement must match decimal precision.
MCQs. no. 97
Which of the following quantities has dimensions [T]?
a. Velocity
b. Time
c. Acceleration
d. Frequency
Correct answer is option b. Time
Explanation:
Time is a base quantity with dimension [T].
MCQs. no. 98
The dimensional formula of frequency is:
a. [T]
b. [T⁻¹]
c. [LT⁻¹]
d. [L⁻¹T]
Correct answer is option b. [T⁻¹]
Explanation:
Frequency = 1/time.
MCQs. no. 99
Which of the following quantities has no dimensions?
a. Angle
b. Velocity
c. Force
d. Work
Correct answer is option a. Angle
Explanation:
Angle is the ratio of arc length to radius, so it is dimensionless.
MCQs. no. 100
The ratio of torque (τ) to mass (m), , has dimensions of:
a. [L² T⁻²]
b. [L² T⁻¹]
c. [L T⁻²]
d. [L²]
Correct Answer: a. [L² T⁻²]
Explanation:
- τ (torque) = F × r → [M L T⁻²][L] = [M L² T⁻²]
- Divide by m → [M L² T⁻²] / [M] = [L² T⁻²]
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