Metrology and Measurement: Topic-Wise MCQs (Set

7) and Formula Sheet

Contents
1 Fundamentals of Measurement . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Types of Errors in Measurement . . . . . . . . . . . . . . . . . . . . . . . 3

3 Length Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Limits, Fits, and Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5 Gauging Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6 Comparators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7 Metrology in Quality Assurance . . . . . . . . . . . . . . . . . . . . . . . 13

8 Measurement of Geometric Forms . . . . . . . . . . . . . . . . . . . . . . 15

9 Slip Gauges (Johansson Gauges) . . . . . . . . . . . . . . . . . . . . . . . 17

10 Surface Finish Measurement . . . . . . . . . . . . . . . . . . . . . . . . . 19

11 Coordinate Measuring Machines (CMM) . . . . . . . . . . . . . . . . . 21

12 Machine Vision in Metrology . . . . . . . . . . . . . . . . . . . . . . . . . 23

13 Optical Metrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

14 Laser Interferometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

15 Nano Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

16 Formula Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

1
1 Fundamentals of Measurement
1. What is the core purpose of measurement in engineering?
a) To enhance product aesthetics
b) To verify dimensional specifications
c) To reduce material costs
d) To accelerate production
Answer: b
2. Accuracy is best described as:
a) Repeatability of results
b) Proximity to the true value
c) Smallest measurable unit
d) Speed of measurement
Answer: b
3. Precision in measurement refers to:
a) Closeness to true value
b) Consistency of repeated measurements
c) Instrument calibration
d) Measurement range
Answer: b
4. Which term defines an instrument’s ability to detect small changes?
a) Accuracy
b) Sensitivity
c) Resolution
d) Calibration
Answer: b
5. Resolution indicates:
a) Error correction capability
b) Smallest detectable increment
c) True value alignment
d) Measurement consistency
Answer: b
6. What can adversely affect measurement accuracy?

2
 a) Stable humidity
b) Temperature fluctuations
c) High resolution
d) Frequent calibration
Answer: b
7. Which ensures measurement reliability?
a) Production efficiency
b) Regular instrument calibration
c) Material optimization
d) Market analysis
Answer: b
8. A precise but inaccurate measurement suggests:
a) Random errors
b) Consistent bias
c) High sensitivity
d) Correct calibration
Answer: b
9. Metrology is vital for:
a) Cost reduction
b) Precise measurements
c) Product marketing
d) Material sourcing
Answer: b
10. Sensitivity measures an instrument’s:
a) Error tolerance
b) Response to small changes
c) Calibration frequency
d) Measurement speed
Answer: b

2 Types of Errors in Measurement

1. Systematic errors result from:

3
 a) Unpredictable fluctuations
b) Fixed instrument issues
c) Operator negligence
d) Random noise
Answer: b
2. Random errors are caused by:
a) Consistent calibration errors
b) Variable environmental factors
c) Human miscalculations
d) Instrument degradation
Answer: b
3. Gross errors typically arise from:
a) Instrument wear
b) Human error
c) Stable conditions
d) Systematic deviations
Answer: b
4. Which error can be mitigated by averaging measurements?
a) Systematic error
b) Random error
c) Gross error
d) Instrumental error
Answer: b
5. An example of a systematic error is:
a) Random vibration
b) Misaligned instrument
c) Operator fatigue
d) Humidity changes
Answer: b
6. Systematic errors are addressed by:
a) Increasing measurement speed
b) Correcting instrument settings

4
 c) Taking multiple readings
d) Changing operators
Answer: b
7. Random errors primarily affect:
a) Measurement accuracy
b) Measurement precision
c) Instrument resolution
d) Calibration frequency
Answer: b
8. Gross errors are reduced by:
a) Using low-cost tools
b) Improving operator training
c) Increasing environmental noise
d) Reducing calibration checks
Answer: b
9. Which error varies unpredictably?
a) Systematic error
b) Random error
c) Gross error
d) Calibration error
Answer: b
10. Gross errors are distinct due to:
a) Consistency
b) Human causation
c) Randomness
d) Instrument specificity
Answer: b

3 Length Standards
1. International standards promote:
a) Local production efficiency
b) Global measurement uniformity

5
 c) Temporary calibration
d) Simplified manufacturing
Answer: b
2. Primary standards serve as:
a) Daily measurement tools
b) Calibration references
c) Production gauges
d) Material testers
Answer: b
3. Secondary standards are derived from:
a) Working standards
b) Primary standards
c) Shop floor instruments
d) International artifacts
Answer: b
4. Working standards are used for:
a) Laboratory calibration
b) Routine measurements
c) International agreements
d) Primary standard creation
Answer: b
5. The SI unit for length is defined by:
a) A physical prototype
b) Light travel distance
c) Material density
d) Earth’s radius
Answer: b
6. Which standard is most accurate?
a) Working standard
b) Secondary standard
c) Primary standard
d) Shop floor standard

6
 Answer: c
7. Primary standards are often made of:
a) Steel
b) Platinum-iridium
c) Aluminum
d) Ceramic
Answer: b
8. Working standards are:
a) Highly precise
b) Practical for daily use
c) Non-portable
d) Expensive
Answer: b
9. Secondary standards calibrate:
a) Primary standards
b) Working standards
c) International standards
d) Shop floor tools
Answer: b
10. Which standard is stored in controlled environments?
a) Working standard
b) Primary standard
c) Secondary standard
d) Shop floor standard
Answer: b

4 Limits, Fits, and Tolerances

1. The ISO system standardizes:
a) Material selection
b) Fits and tolerances
c) Production schedules
d) Inspection methods

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 Answer: b
2. In a hole-basis system, what is constant?
a) Shaft diameter
b) Hole diameter
c) Tolerance range
d) Fit clearance
Answer: b
3. A Go gauge checks:
a) Minimum material condition
b) Maximum material condition
c) Surface texture
d) Geometric alignment
Answer: b
4. A clearance fit allows:
a) Fixed assembly
b) Relative movement
c) Permanent bonding
d) No tolerance
Answer: b
5. Tolerance refers to:
a) Material strength
b) Permissible variation
c) Surface quality
d) Production cost
Answer: b
6. In a shaft-basis system, what is fixed?
a) Hole size
b) Shaft size
c) Clearance gap
d) Tolerance limit
Answer: b
7. A No-Go gauge verifies:

8
 a) Maximum material condition
b) Minimum material condition
c) Surface finish
d) Part alignment
Answer: b
8. An interference fit ensures:
a) Loose connection
b) Secure assembly
c) Free movement
d) Gap formation
Answer: b
9. A transition fit may result in:
a) Always clearance
b) Always interference
c) Either clearance or interference
d) No contact
Answer: c
10. Fit selection depends on:
a) Product color
b) Assembly requirements
c) Market demand
d) Operator skill
Answer: b

5 Gauging Techniques
1. Plug gauges are designed to measure:
a) External dimensions
b) Internal dimensions
c) Surface roughness
d) Material hardness
Answer: b
2. Ring gauges check:

9
 a) Hole diameters
b) Shaft diameters
c) Thread depths
d) Surface flatness
Answer: b
3. Snap gauges are used for:
a) Internal holes
b) External dimensions
c) Surface finish
d) Geometric forms
Answer: b
4. Feeler gauges measure:
a) Hole depth
b) Gap width
c) Thread pitch
d) Surface flatness
Answer: b
5. Which gauge is suitable for rapid inspection?
a) Micrometer
b) Snap gauge
c) CMM
d) Vernier caliper
Answer: b
6. Limit gauges provide:
a) Precise measurements
b) Go/No-Go assessment
c) Surface analysis
d) Complex calculations
Answer: b
7. Thread gauges inspect:
a) Surface texture
b) Thread dimensions

10
 c) External diameters
d) Flat surfaces
Answer: b
8. Gauges are typically made from:
a) Plastic
b) Tool steel
c) Aluminum
d) Wood
Answer: b
9. Which gauge is used for small clearances?
a) Plug gauge
b) Feeler gauge
c) Ring gauge
d) CMM
Answer: b
10. A limitation of plug gauges is:
a) High accuracy
b) Limited to internal use
c) Low cost
d) Easy calibration
Answer: b

6 Comparators
1. Mechanical comparators use:
a) Light projection
b) Mechanical amplification
c) Air flow
d) Electrical signals
Answer: b
2. Optical comparators rely on:
a) Gear systems
b) Shadow projection

11
 c) Air pressure
d) Voltage changes
Answer: b
3. Pneumatic comparators measure using:
a) Light reflection
b) Air pressure changes
c) Mechanical levers
d) Electrical current
Answer: b
4. Electrical comparators detect:
a) Air flow
b) Voltage variations
c) Light intensity
d) Gear movement
Answer: b
5. An advantage of pneumatic comparators is:
a) Low cost
b) High sensitivity
c) Complex setup
d) Slow response
Answer: b
6. Optical comparators are ideal for:
a) Large components
b) Profile inspection
c) Rough surfaces
d) Internal holes
Answer: b
7. A disadvantage of mechanical comparators is:
a) High precision
b) Mechanical wear
c) Fast operation
d) Low maintenance

12
 Answer: b
8. Electrical comparators are suitable for:
a) Manual inspection
b) Automated systems
c) Large parts
d) Rough surfaces
Answer: b
9. Which comparator uses magnified images?
a) Pneumatic
b) Optical
c) Mechanical
d) Electrical
Answer: b
10. Comparator reliability is improved by:
a) High vibration
b) Regular calibration
c) Low-cost parts
d) Manual adjustments
Answer: b

7 Metrology in Quality Assurance

1. Metrology in QA ensures:
a) Increased production speed
b) Product conformity
c) Reduced material costs
d) Simplified processes
Answer: b
2. Statistical Process Control (SPC) uses:
a) Random inspections
b) Control charts
c) Manual gauges
d) Visual checks

13
 Answer: b
3. Inspection in QA verifies:
a) Production costs
b) Product specifications
c) Employee performance
d) Market demand
Answer: b
4. SPC monitors:
a) Material properties
b) Process stability
c) Production costs
d) Operator performance
Answer: b
5. A key benefit of SPC is:
a) Higher defect rates
b) Reduced waste
c) Increased costs
d) Lower accuracy
Answer: b
6. Which tool is used in SPC to track process performance?
a) Gantt Chart
b) X-bar Chart
c) SWOT Analysis
d) Pareto Chart
Answer: b
7. Acceptance sampling involves:
a) Inspecting all units
b) Testing a sample
c) Process redesign
d) Employee training
Answer: b
8. Metrology supports QA by providing:

14
 a) Cost estimates
b) Precise measurements
c) Production schedules
d) Marketing strategies
Answer: b
9. Control charts in SPC identify:
a) Material defects
b) Process variations
c) Design flaws
d) Market trends
Answer: b
10. SPC enhances QA by:
a) Increasing tolerances
b) Minimizing defects
c) Reducing inspections
d) Manual processes
Answer: b

8 Measurement of Geometric Forms

1. Flatness is defined as:
a) Surface curvature
b) Deviation from a plane
c) Material thickness
d) Edge sharpness
Answer: b
2. Straightness measures deviation from:
a) A curved line
b) A straight line
c) A circular path
d) A random path
Answer: b
3. Roundness assesses deviation from:

15
 a) A perfect circle
b) A flat surface
c) A straight edge
d) A square shape
Answer: a
4. Which tool measures flatness?
a) Micrometer
b) Optical flat
c) Snap gauge
d) Vernier caliper
Answer: b
5. Cylindricity is important for:
a) Flat plates
b) Cylindrical components
c) Angular surfaces
d) Flexible parts
Answer: b
6. Roundness is measured using:
a) Feeler gauge
b) Roundness tester
c) Plug gauge
d) Profilometer
Answer: b
7. Parallelism ensures:
a) Curved alignment
b) Consistent spacing
c) Surface roughness
d) Material density
Answer: b
8. Which method measures flatness via light patterns?
a) Profilometry
b) Interferometry

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 c) Gauging
d) Micrometry
Answer: b
9. Straightness is critical for:
a) Decorative surfaces
b) Precision shafts
c) Non-critical parts
d) Flexible components
Answer: b
10. Geometric form measurement requires:
a) Low cost
b) High precision
c) Simple instruments
d) Fast processes
Answer: b

9 Slip Gauges (Johansson Gauges)

1. Slip gauges are primarily used for:
a) Surface polishing
b) Precision calibration
c) Material cutting
d) Production speed
Answer: b
2. Wringing in slip gauges refers to:
a) Mechanical clamping
b) Molecular adhesion
c) Magnetic bonding
d) Chemical adhesion
Answer: b
3. Slip gauges are categorized by:
a) Material composition
b) Accuracy grades

17
 c) Production technique
d) Surface roughness
Answer: b
4. The material of slip gauges is typically:
a) Aluminum
b) Hardened steel
c) Plastic
d) Ceramic
Answer: b
5. Slip gauges are commonly used in:
a) Mass production
b) Instrument calibration
c) Rough measurements
d) Material testing
Answer: b
6. Which slip gauge grade is most precise?
a) Grade 2
b) Grade 1
c) Grade 0
d) Grade 3
Answer: c
7. Wringing ensures slip gauges:
a) Remain loose
b) Adhere tightly
c) Are misaligned
d) Are damaged
Answer: b
8. Slip gauges are sensitive to:
a) Temperature variations
b) Low humidity
c) High durability
d) Simple handling

18
 Answer: a
9. Which grade is suitable for inspection purposes?
a) Grade 0
b) Grade 1
c) Grade 2
d) Grade 00
Answer: b
10. A limitation of slip gauges is:
a) High accuracy
b) Need for clean surfaces
c) Low cost
d) Fast setup
Answer: b

10 Surface Finish Measurement

1. CLA in surface finish stands for:
a) Center Line Average
b) Critical Line Assessment
c) Constant Level Analysis
d) Central Limit Average
Answer: a
2. RMS measures surface roughness as:
a) Average deviation
b) Root mean square deviation
c) Peak height
d) Valley depth
Answer: b
3. Ra represents:
a) Maximum roughness
b) Average roughness
c) Total roughness
d) Peak-to-valley height

19
 Answer: b
4. Rz quantifies:
a) Average roughness
b) Peak-to-valley distance
c) Surface flatness
d) Material hardness
Answer: b
5. A profilometer is used to measure:
a) Surface texture
b) Material strength
c) Geometric dimensions
d) Production rate
Answer: a
6. Surface finish is influenced by:
a) Machining parameters
b) Operator salary
c) Market demand
d) Product weight
Answer: a
7. Which unit is used for roughness measurement?
a) Millimeter
b) Micrometer
c) Newton
d) Pascal
Answer: b
8. Contact profilometry involves:
a) Laser scanning
b) Stylus tracing
c) Optical imaging
d) Visual inspection
Answer: b
9. A lower Ra value indicates:

20
 a) Rougher surface
b) Smoother surface
c) Higher strength
d) Greater thickness
Answer: b
10. Surface finish affects:
a) Material cost
b) Component functionality
c) Production speed
d) Market trends
Answer: b

11 Coordinate Measuring Machines (CMM)

1. CMMs are used to measure:
a) Surface roughness
b) 3D coordinates
c) Material hardness
d) Production speed
Answer: b
2. A bridge CMM is characterized by:
a) Portability
b) Fixed gantry structure
c) Articulated arms
d) Cantilever design
Answer: b
3. The most common CMM probe is:
a) Laser probe
b) Touch probe
c) Air probe
d) Thermal probe
Answer: b
4. CMM operation relies on:

21
 a) Manual adjustments
b) Computer software
c) Visual inspection
d) Random sampling
Answer: b
5. A key advantage of CMM is:
a) Low cost
b) High accuracy
c) Slow measurement
d) Simple maintenance
Answer: b
6. Which CMM type is used for small parts?
a) Bridge CMM
b) Cantilever CMM
c) Portable CMM
d) Gantry CMM
Answer: b
7. CMM accuracy is affected by:
a) Environmental stability
b) Manual operation
c) Low-cost probes
d) High vibration
Answer: a
8. Non-contact probes in CMM include:
a) Touch probes
b) Laser probes
c) Stylus probes
d) Mechanical probes
Answer: b
9. A limitation of CMM is:
a) Fast setup
b) High initial investment

22
 c) Low precision
d) Simple operation
Answer: b
10. CMM is commonly used for:
a) Material cutting
b) Dimensional inspection
c) Surface polishing
d) Product assembly
Answer: b

12 Machine Vision in Metrology

1. Machine vision in metrology enables:
a) Manual gauging
b) Automated inspection
c) Material testing
d) Production planning
Answer: b
2. 2D vision systems are used for:
a) Complex 3D shapes
b) Flat surface dimensions
c) Material strength
d) Surface roughness
Answer: b
3. 3D vision systems measure:
a) Planar features only
b) Spatial geometries
c) Material density
d) Production speed
Answer: b
4. AI in vision systems enhances:
a) Manual inspection
b) Defect identification

23
 c) Material cutting
d) Operator training
Answer: b
5. A key component of vision systems is:
a) Mechanical gauge
b) High-resolution camera
c) Air sensor
d) Plug gauge
Answer: b
6. An advantage of machine vision is:
a) High maintenance
b) Rapid inspection
c) Low accuracy
d) Complex setup
Answer: b
7. Vision system accuracy depends on:
a) Operator experience
b) Lighting quality
c) Material color
d) Market demand
Answer: b
8. Machine vision is best suited for:
a) Low-speed inspection
b) High-volume production
c) Manual measurements
d) Material testing
Answer: b
9. AI improves vision systems by:
a) Simplifying mechanics
b) Enhancing image analysis
c) Reducing automation
d) Manual calibration

24
 Answer: b
10. A challenge of machine vision is:
a) Low cost
b) Initial setup complexity
c) High speed
d) Simple maintenance
Answer: b

13 Optical Metrology
1. Optical flats are used to assess:
a) Surface roughness
b) Surface flatness
c) Material hardness
d) Production speed
Answer: b
2. Interferometry relies on:
a) Mechanical contact
b) Light wave interference
c) Air pressure
d) Electrical signals
Answer: b
3. Interference fringes reveal:
a) Material thickness
b) Surface irregularities
c) Production rate
d) Operator errors
Answer: b
4. Optical flats are typically made of:
a) Steel
b) Fused silica
c) Plastic
d) Aluminum

25
 Answer: b
5. An advantage of optical metrology is:
a) Low precision
b) Non-contact measurement
c) High cost
d) Slow process
Answer: b
6. Interferometry requires:
a) Incandescent light
b) Monochromatic light
c) Fluorescent light
d) LED light
Answer: b
7. Optical metrology is best for:
a) Rough surfaces
b) Precision surfaces
c) Large components
d) Flexible materials
Answer: b
8. A limitation of optical flats is:
a) High durability
b) Limited to flat surfaces
c) Low cost
d) Fast measurement
Answer: b
9. What improves optical metrology accuracy?
a) High vibration
b) Stable environment
c) Manual operation
d) Low-cost optics
Answer: b
10. Optical metrology measures:

26
 a) Material strength
b) Surface quality
c) Production cost
d) Operator performance
Answer: b

14 Laser Interferometry
1. Laser interferometry is used for:
a) Surface roughness
b) High-precision measurements
c) Material strength
d) Production speed
Answer: b
2. The Michelson interferometer measures:
a) Air pressure
b) Distance changes
c) Mechanical force
d) Electrical current
Answer: b
3. Twyman-Green interferometer is used to:
a) Test optical components
b) Measure material thickness
c) Assess production rate
d) Check operator skill
Answer: a
4. A key feature of laser interferometry is:
a) Low accuracy
b) High resolution
c) Simple setup
d) High cost
Answer: b
5. Laser interferometry is applied in:

27
 a) Material cutting
b) Instrument calibration
c) Surface polishing
d) Product assembly
Answer: b
6. Interference patterns in laser interferometry indicate:
a) Surface texture
b) Dimensional changes
c) Material defects
d) Production errors
Answer: b
7. Accuracy in laser interferometry is affected by:
a) Air turbulence
b) Operator salary
c) Material type
d) Market demand
Answer: a
8. A challenge of laser interferometry is:
a) Low precision
b) Need for stable conditions
c) Fast setup
d) Low cost
Answer: b
9. Which interferometer tests lens quality?
a) Michelson
b) Twyman-Green
c) Pneumatic
d) Electrical
Answer: b
10. Laser interferometry requires:
a) Coherent light source
b) Incandescent light

28
 c) Mechanical contact
d) Manual gauging
Answer: a

15 Nano Measurements
1. Nanometrology focuses on:
a) Large-scale dimensions
b) Nano-scale features
c) Material strength
d) Production speed
Answer: b
2. AFM is used to measure:
a) Surface topography
b) Material density
c) Production rate
d) Geometric forms
Answer: a
3. STM stands for:
a) Scanning Tunneling Microscopy
b) Surface Testing Microscopy
c) Standard Tunneling Measurement
d) Scanning Thermal Microscopy
Answer: a
4. STM provides:
a) Low resolution
b) Atomic-level imaging
c) Large-scale measurement
d) Fast processing
Answer: b
5. A common sensor in nanometrology is:
a) Piezoelectric sensor
b) Air sensor

29
 c) Mechanical sensor
d) Thermal sensor
Answer: a
6. An advantage of AFM is:
a) High speed
b) Nanoscale resolution
c) Low cost
d) Simple operation
Answer: b
7. Nanometrology is essential for:
a) Bulk manufacturing
b) Nanotechnology research
c) Material cutting
d) Product assembly
Answer: b
8. A limitation of STM is:
a) High speed
b) Conductive sample requirement
c) Low cost
d) Large scan area
Answer: b
9. Nano measurements require:
a) Vibration isolation
b) High temperature
c) Manual gauges
d) Low precision
Answer: a
10. AFM measures surface features using:
a) Light waves
b) Cantilever deflection
c) Air pressure
d) Electrical current

30
 Answer: b

16 Formula Sheet

Table 1: Key Formulas in Metrology and Measurement

Topic Formula
Tolerance Range Tolerance = Upper Limit − Lower Limit
∫L
Surface Roughness (Ra) Ra = L1 0 |z(x)| dx
z(x) = Profile deviation, L = Sampling length
λ
Interference Fringe Spacing ∆x = 2 sin θ
λ = Wavelength, θ = Angle of incidence
Least Count
Resolution of CMM Resolution = Probe
√∑ Sensitivity
(xi −x̄)2
Standard Deviation (SPC) σ = n
xi = Data point, x̄ = Mean, n = Sample size

31