Metrology and Measurement: Topic-Wise MCQs (Set

3) 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 objective of measurement in engineering?
a) To reduce material costs
b) To ensure product accuracy
c) To simplify manufacturing
d) To increase production speed
Answer: b
2. Accuracy is best described as:
a) Repeatability of results
b) Closeness to the true value
c) Smallest measurable unit
d) Instrument response speed
Answer: b
3. Precision refers to:
a) Agreement with true value
b) Consistency of measurements
c) Calibration frequency
d) Measurement range
Answer: b
4. Which property indicates an instrument’s ability to detect small changes?
a) Resolution
b) Sensitivity
c) Accuracy
d) Precision
Answer: b
5. Resolution in measurement is:
a) Error magnitude
b) Smallest detectable increment
c) True value proximity
d) Measurement consistency
Answer: b
6. What can degrade measurement accuracy?

2
 a) Controlled environment
b) Humidity fluctuations
c) High sensitivity
d) Regular calibration
Answer: b
7. What ensures reliable measurements?
a) Market demand
b) Instrument maintenance
c) Production volume
d) Material type
Answer: b
8. A measurement with high precision but low accuracy shows:
a) Random errors
b) Consistent bias
c) High resolution
d) True value alignment
Answer: b
9. Metrology primarily focuses on:
a) Cost reduction
b) Precise measurements
c) Process automation
d) Material selection
Answer: b
10. Which term describes the smallest change an instrument can measure?
a) Accuracy
b) Resolution
c) Tolerance
d) Calibration
Answer: b

2 Types of Errors in Measurement

1. Systematic errors are caused by:

3
 a) Unpredictable factors
b) Consistent inaccuracies
c) Operator oversight
d) Random noise
Answer: b
2. Random errors arise from:
a) Fixed instrument issues
b) Variable external conditions
c) Human calculation errors
d) Calibration drifts
Answer: b
3. Gross errors are typically due to:
a) Environmental changes
b) Human blunders
c) Instrument wear
d) Systematic biases
Answer: b
4. Which error type can be reduced by taking multiple measurements?
a) Systematic error
b) Random error
c) Gross error
d) Calibration error
Answer: b
5. An example of a systematic error is:
a) Operator misreading
b) Misaligned instrument
c) Temperature variation
d) Random vibration
Answer: b
6. Systematic errors are corrected by:
a) Increasing measurement frequency
b) Adjusting instrument settings

4
 c) Ignoring small errors
d) Changing operators
Answer: b
7. Random errors impact:
a) Measurement accuracy
b) Measurement repeatability
c) Instrument resolution
d) Calibration standards
Answer: b
8. Gross errors are minimized through:
a) Environmental stabilization
b) Careful operator practices
c) Low-precision instruments
d) Reduced calibration
Answer: b
9. Which error varies unpredictably?
a) Systematic error
b) Random error
c) Gross error
d) Instrumental error
Answer: b
10. Gross errors differ from others because they are:
a) Consistent
b) Human-induced
c) Randomly distributed
d) Instrument-specific
Answer: b

3 Length Standards
1. International standards ensure:
a) Local production efficiency
b) Universal measurement consistency

5
 c) Temporary calibration
d) Shop floor flexibility
Answer: b
2. Primary standards are used for:
a) Routine inspections
b) Defining reference values
c) Production gauging
d) Material testing
Answer: b
3. Secondary standards are based on:
a) Working standards
b) Primary standards
c) Shop floor tools
d) International agreements
Answer: b
4. Working standards are employed in:
a) High-precision labs
b) Manufacturing environments
c) International calibration
d) Primary standard development
Answer: b
5. The modern definition of a meter relies on:
a) A physical prototype
b) Light travel time
c) Material expansion
d) Earth’s diameter
Answer: b
6. Which standard offers the highest precision?
a) Working standard
b) Secondary standard
c) Primary standard
d) Shop floor standard

6
 Answer: c
7. Primary standards are often made from:
a) Steel
b) Platinum-iridium
c) Aluminum
d) Ceramic
Answer: b
8. Working standards are characterized by:
a) Maximum accuracy
b) Practical application
c) Complex calibration
d) Non-portability
Answer: b
9. Secondary standards calibrate:
a) Primary standards
b) Working standards
c) International standards
d) Prototype artifacts
Answer: b
10. Which standard is most accessible for daily use?
a) Primary standard
b) Secondary standard
c) Working standard
d) International standard
Answer: c

4 Limits, Fits, and Tolerances

1. The ISO system standardizes:
a) Production rates
b) Dimensional fits
c) Material properties
d) Inspection protocols

7
 Answer: b
2. In a hole-basis system, what is standardized?
a) Shaft diameter
b) Hole diameter
c) Tolerance range
d) Fit type
Answer: b
3. A Go gauge verifies:
a) Minimum material condition
b) Maximum material condition
c) Surface finish
d) Part alignment
Answer: b
4. A clearance fit provides:
a) Tight assembly
b) Space between components
c) Fixed connection
d) No movement
Answer: b
5. Tolerance defines:
a) Material strength
b) Acceptable dimension variation
c) Surface quality
d) Production speed
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 checks:

8
 a) Maximum material condition
b) Minimum material condition
c) Surface texture
d) Geometric form
Answer: b
8. An interference fit ensures:
a) Loose assembly
b) Tight connection
c) Free movement
d) Gap formation
Answer: b
9. A transition fit may result in:
a) Always clearance
b) Always interference
c) Clearance or interference
d) No contact
Answer: c
10. Fit selection depends on:
a) Product aesthetics
b) Functional requirements
c) Market trends
d) Operator preference
Answer: b

5 Gauging Techniques
1. Plug gauges measure:
a) External diameters
b) Internal diameters
c) Surface roughness
d) Material thickness
Answer: b
2. Ring gauges are used for:

9
 a) Hole dimensions
b) Shaft dimensions
c) Thread angles
d) Flatness
Answer: b
3. Snap gauges assess:
a) Internal features
b) External dimensions
c) Surface finish
d) Geometric shapes
Answer: b
4. Feeler gauges check:
a) Hole depth
b) Gap thickness
c) Thread pitch
d) Surface flatness
Answer: b
5. Which gauge is ideal for quick checks?
a) Vernier caliper
b) Plug gauge
c) Micrometer
d) CMM
Answer: b
6. Limit gauges are used for:
a) Precise measurements
b) Pass/fail inspection
c) Surface analysis
d) Complex setups
Answer: b
7. Thread gauges verify:
a) Surface texture
b) Thread accuracy

10
 c) External diameters
d) Flat surfaces
Answer: b
8. Gauges are commonly made of:
a) Plastic
b) Hardened steel
c) Aluminum
d) Wood
Answer: b
9. Which gauge is simple and portable?
a) CMM
b) Feeler gauge
c) Optical comparator
d) Profilometer
Answer: b
10. A limitation of ring gauges is:
a) High durability
b) Limited to shafts
c) Low cost
d) Easy calibration
Answer: b

6 Comparators
1. Mechanical comparators operate using:
a) Air pressure
b) Mechanical linkages
c) Light projection
d) Electrical signals
Answer: b
2. Optical comparators function via:
a) Gear systems
b) Image magnification

11
 c) Air flow
d) Voltage changes
Answer: b
3. Pneumatic comparators rely on:
a) Light reflection
b) Air pressure variations
c) Mechanical levers
d) Electrical current
Answer: b
4. Electrical comparators measure:
a) Air flow
b) Voltage differences
c) Light intensity
d) Gear movement
Answer: b
5. An advantage of optical comparators is:
a) Low cost
b) High magnification
c) Complex maintenance
d) Slow response
Answer: b
6. Pneumatic comparators are best for:
a) Rough surfaces
b) Smooth surfaces
c) Large components
d) Complex geometries
Answer: b
7. A drawback of mechanical comparators is:
a) High accuracy
b) Component wear
c) Fast operation
d) Low maintenance

12
 Answer: b
8. Electrical comparators are suited for:
a) Manual inspection
b) Automated measurement
c) Large parts
d) Rough surfaces
Answer: b
9. Which comparator projects a shadow image?
a) Mechanical
b) Optical
c) Pneumatic
d) Electrical
Answer: b
10. Comparator accuracy is enhanced by:
a) High vibration
b) Proper calibration
c) Low-cost parts
d) Manual operation
Answer: b

7 Metrology in Quality Assurance

1. Metrology in quality assurance ensures:
a) Reduced production time
b) Product specification adherence
c) Increased material usage
d) Simplified designs
Answer: b
2. Statistical Process Control (SPC) employs:
a) Random sampling
b) Control charts
c) Manual inspections
d) Visual assessments

13
 Answer: b
3. Inspection in QA confirms:
a) Production costs
b) Dimensional accuracy
c) Employee efficiency
d) Market demand
Answer: b
4. SPC is used to monitor:
a) Material properties
b) Process consistency
c) Production schedules
d) Operator performance
Answer: b
5. A benefit of SPC is:
a) Increased defects
b) Reduced variability
c) Higher costs
d) Lower precision
Answer: b
6. Which tool tracks process performance in SPC?
a) Gantt Chart
b) Control Chart
c) Pareto Chart
d) SWOT Analysis
Answer: b
7. Acceptance sampling tests:
a) All products
b) A sample of products
c) Process designs
d) Operator skills
Answer: b
8. Metrology in QA provides:

14
 a) Cost savings
b) Reliable measurements
c) Production speed
d) Market insights
Answer: b
9. Control charts detect:
a) Material defects
b) Process deviations
c) Design errors
d) Market trends
Answer: b
10. SPC improves QA by:
a) Increasing tolerances
b) Minimizing defects
c) Reducing inspections
d) Manual processes
Answer: b

8 Measurement of Geometric Forms

1. Flatness measures:
a) Surface curvature
b) Deviation from a plane
c) Material thickness
d) Edge alignment
Answer: b
2. Straightness evaluates deviation from:
a) A curved path
b) A linear path
c) A circular path
d) A random path
Answer: b
3. Roundness checks deviation from:

15
 a) A straight line
b) A perfect circle
c) A flat surface
d) A square shape
Answer: b
4. Which instrument measures flatness?
a) Vernier caliper
b) Optical flat
c) Feeler gauge
d) Snap gauge
Answer: b
5. Cylindricity assesses:
a) Flat surfaces
b) Cylindrical forms
c) Angular deviations
d) Surface texture
Answer: b
6. Roundness is measured with:
a) Micrometer
b) Roundness tester
c) Plug gauge
d) CMM
Answer: b
7. Parallelism ensures:
a) Curved alignment
b) Uniform spacing
c) Surface roughness
d) Material strength
Answer: b
8. Flatness measurement often uses:
a) Profilometry
b) Interferometry

16
 c) Gauging
d) Micrometry
Answer: b
9. Straightness is critical for:
a) Flexible components
b) Machine shafts
c) Decorative parts
d) Non-functional surfaces
Answer: b
10. Geometric form measurement requires:
a) Low precision
b) High precision
c) Simple tools
d) Fast processes
Answer: b

9 Slip Gauges (Johansson Gauges)

1. Slip gauges are used for:
a) Surface finishing
b) Precision calibration
c) Material cutting
d) Production speed
Answer: b
2. Wringing in slip gauges involves:
a) Mechanical fastening
b) Surface adhesion
c) Magnetic bonding
d) Chemical bonding
Answer: b
3. Slip gauges are classified by:
a) Material type
b) Accuracy grade

17
 c) Production method
d) Surface texture
Answer: b
4. Slip gauges are typically made of:
a) Aluminum
b) Hardened steel
c) Plastic
d) Wood
Answer: b
5. A common use of slip gauges is:
a) Surface polishing
b) Setting up instruments
c) Material testing
d) Product assembly
Answer: b
6. The most accurate slip gauge grade is:
a) Grade 0
b) Grade 1
c) Grade 2
d) Grade 3
Answer: a
7. Wringing ensures slip gauges:
a) Stay loose
b) Stick together
c) Are misaligned
d) Are damaged
Answer: b
8. Slip gauges are used in:
a) Rough measurements
b) Precision setups
c) Mass production
d) Material cutting

18
 Answer: b
9. A limitation of slip gauges is:
a) High durability
b) Sensitivity to dirt
c) Low cost
d) Easy handling
Answer: b
10. Which grade is used for workshop measurements?
a) Grade 0
b) Grade 1
c) Grade 2
d) Grade 00
Answer: c

10 Surface Finish Measurement

1. CLA measures:
a) Peak height
b) Average roughness
c) Total roughness
d) Valley depth
Answer: b
2. RMS in surface finish refers to:
a) Roughness Mean Square
b) Root Mean Square
c) Random Measurement Scale
d) Roughness Magnitude Scale
Answer: b
3. Ra denotes:
a) Maximum roughness
b) Average roughness
c) Peak-to-valley height
d) Total roughness

19
 Answer: b
4. Rz measures:
a) Average roughness
b) Peak-to-valley height
c) Surface flatness
d) Material strength
Answer: b
5. A profilometer evaluates:
a) Surface texture
b) Material hardness
c) Geometric forms
d) Production speed
Answer: a
6. Surface finish is affected by:
a) Tool wear
b) Operator salary
c) Market demand
d) Product color
Answer: a
7. The unit for surface roughness is:
a) Newton
b) Micrometer
c) Pascal
d) Joule
Answer: b
8. Contact profilometry uses:
a) Laser scanning
b) Stylus movement
c) Optical imaging
d) Visual inspection
Answer: b
9. A higher Ra value suggests:

20
 a) Smoother surface
b) Rougher surface
c) Stronger material
d) Flatter surface
Answer: b
10. Surface finish impacts:
a) Material cost
b) Component performance
c) Production speed
d) Market trends
Answer: b

11 Coordinate Measuring Machines (CMM)

1. CMMs measure:
a) Surface roughness
b) Geometric dimensions
c) Material strength
d) Production speed
Answer: b
2. A bridge CMM features:
a) Articulated arms
b) Fixed gantry
c) Portability
d) Cantilever structure
Answer: b
3. A typical CMM probe is:
a) Air probe
b) Touch probe
c) Magnetic probe
d) Thermal probe
Answer: b
4. CMM operation requires:

21
 a) Manual gauging
b) Software control
c) Visual inspection
d) Random sampling
Answer: b
5. An advantage of CMM is:
a) Low accuracy
b) High precision
c) High cost
d) Slow measurement
Answer: b
6. Which CMM is best for large components?
a) Portable CMM
b) Bridge CMM
c) Cantilever CMM
d) Articulated CMM
Answer: b
7. CMM accuracy is improved by:
a) Temperature control
b) Manual operation
c) Low-cost probes
d) High vibration
Answer: a
8. A non-contact CMM probe is:
a) Touch probe
b) Laser probe
c) Stylus probe
d) Mechanical probe
Answer: b
9. A limitation of CMM is:
a) High speed
b) High setup cost

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

12 Machine Vision in Metrology

1. Machine vision in metrology supports:
a) Manual inspection
b) Automated inspection
c) Material testing
d) Production planning
Answer: b
2. 2D vision systems measure:
a) Complex 3D shapes
b) Flat dimensions
c) Material strength
d) Surface roughness
Answer: b
3. 3D vision systems assess:
a) Planar surfaces only
b) Spatial geometries
c) Material density
d) Production speed
Answer: b
4. AI in machine vision improves:
a) Manual gauging
b) Defect detection

23
 c) Material cutting
d) Operator training
Answer: b
5. A core component of vision systems is:
a) Air sensor
b) Camera
c) Mechanical lever
d) Plug gauge
Answer: b
6. A benefit of machine vision is:
a) High cost
b) Fast inspection
c) Low accuracy
d) Complex maintenance
Answer: b
7. Vision system accuracy relies on:
a) Operator experience
b) Proper lighting
c) Material color
d) Market demand
Answer: b
8. Machine vision is ideal for:
a) Low-volume production
b) High-speed inspection
c) Manual measurements
d) Material testing
Answer: b
9. AI enhances vision systems by:
a) Simplifying mechanics
b) Improving pattern recognition
c) Reducing automation
d) Manual calibration

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

13 Optical Metrology
1. Optical flats measure:
a) Surface roughness
b) Surface flatness
c) Material hardness
d) Production speed
Answer: b
2. Interferometry uses:
a) Mechanical contact
b) Light wave interference
c) Air pressure
d) Electrical signals
Answer: b
3. Interference fringes indicate:
a) Material thickness
b) Surface deviations
c) Production rate
d) Operator errors
Answer: b
4. Optical flats are made of:
a) Steel
b) Quartz
c) Plastic
d) Aluminum

25
 Answer: b
5. A benefit of optical metrology is:
a) High cost
b) Non-contact measurement
c) Low precision
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 suited for:
a) Rough surfaces
b) High-precision surfaces
c) Large components
d) Flexible materials
Answer: b
8. A limitation of optical flats is:
a) High durability
b) Flat surface requirement
c) Low cost
d) Fast measurement
Answer: b
9. Optical metrology accuracy depends on:
a) High vibration
b) Stable conditions
c) Manual operation
d) Low-cost optics
Answer: b
10. Optical metrology assesses:

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

14 Laser Interferometry
1. Laser interferometry measures:
a) Surface roughness
b) Precise distances
c) Material strength
d) Production speed
Answer: b
2. The Michelson interferometer uses:
a) Air pressure
b) Laser beams
c) Mechanical gears
d) Electrical signals
Answer: b
3. Twyman-Green interferometer evaluates:
a) Surface flatness
b) Material thickness
c) Production rate
d) Operator skill
Answer: a
4. An advantage of laser interferometry is:
a) Low accuracy
b) High precision
c) Simple setup
d) High cost
Answer: b
5. Laser interferometry is used for:

27
 a) Material cutting
b) Calibration
c) Surface polishing
d) Product assembly
Answer: b
6. Interference patterns in laser interferometry show:
a) Surface texture
b) Dimensional changes
c) Material defects
d) Production errors
Answer: b
7. Laser interferometry is sensitive to:
a) Air turbulence
b) Operator salary
c) Material color
d) Market demand
Answer: a
8. A limitation of laser interferometry is:
a) High speed
b) Complex setup
c) Low cost
d) Simple operation
Answer: b
9. The Michelson interferometer is ideal for:
a) Rough surfaces
b) Precision measurements
c) Large components
d) Flexible materials
Answer: b
10. Laser interferometry accuracy requires:
a) Stable environment
b) Manual operation

28
 c) Low-cost lasers
d) High vibration
Answer: a

15 Nano Measurements
1. Nanometrology examines:
a) Macro-scale features
b) Nano-scale features
c) Material strength
d) Production speed
Answer: b
2. AFM stands for:
a) Automated Force Microscopy
b) Atomic Force Microscopy
c) Advanced Frequency Microscopy
d) Atomic Field Microscopy
Answer: b
3. STM measures:
a) Surface roughness
b) Atomic structures
c) Material thickness
d) Production rate
Answer: b
4. A feature of AFM is:
a) Low resolution
b) High resolution
c) Large-scale measurement
d) Simple operation
Answer: b
5. Nanometrology often uses:
a) Air sensors
b) Piezoelectric sensors

29
 c) Mechanical sensors
d) Thermal sensors
Answer: b
6. An advantage of STM is:
a) Low cost
b) Atomic resolution
c) Fast measurement
d) Simple setup
Answer: b
7. Nanometrology is critical for:
a) Mass production
b) Nanotechnology
c) Material cutting
d) Product assembly
Answer: b
8. A limitation of AFM is:
a) High speed
b) Limited scan area
c) Low cost
d) Simple operation
Answer: b
9. Nano measurements require:
a) Vibration isolation
b) High temperature
c) Manual gauges
d) Low precision
Answer: a
10. STM operates by measuring:
a) Light waves
b) Tunneling current
c) Air pressure
d) Mechanical force

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