Metrology and Measurement: Topic-Wise MCQs 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. Why is measurement essential in engineering?
a) To increase production costs
b) To ensure product quality
c) To reduce design complexity
d) To eliminate inspections
Answer: b
2. What does accuracy refer to in measurement?
a) Consistency of results
b) Closeness to true value
c) Speed of measurement
d) Range of instrument
Answer: b
3. Precision in measurement indicates:
a) True value proximity
b) Repeatability of results
c) Instrument calibration
d) Error magnitude
Answer: b
4. Which factor affects measurement reliability?
a) Operator skill
b) Production speed
c) Market demand
d) Material cost
Answer: a
5. What is the primary goal of metrology?
a) Cost reduction
b) Accurate measurements
c) Process automation
d) Product design
Answer: b
6. Which term describes the smallest measurable unit?

2
 a) Accuracy
b) Precision
c) Resolution
d) Sensitivity
Answer: c
7. What does sensitivity of an instrument measure?
a) Error range
b) Response to input change
c) Measurement speed
d) Calibration frequency
Answer: b
8. Which is a characteristic of a precise instrument?
a) High cost
b) Consistent readings
c) Low maintenance
d) Simple design
Answer: b
9. What reduces measurement accuracy?
a) Calibration
b) Environmental factors
c) High resolution
d) Operator training
Answer: b
10. What is the difference between accuracy and precision?
a) Accuracy is repeatability; precision is true value closeness
b) Accuracy is true value closeness; precision is repeatability
c) Both are identical
d) Accuracy is resolution; precision is sensitivity
Answer: b

2 Types of Errors in Measurement

1. What characterizes systematic errors?

3
 a) Random occurrence
b) Consistent bias
c) Human mistakes
d) Unpredictable variations
Answer: b
2. Random errors are caused by:
a) Instrument calibration
b) Uncontrolled variables
c) Operator negligence
d) Fixed biases
Answer: b
3. Gross errors typically result from:
a) Environmental changes
b) Human mistakes
c) Instrument drift
d) Material defects
Answer: b
4. Which error can be reduced by calibration?
a) Random error
b) Systematic error
c) Gross error
d) All errors
Answer: b
5. What is a source of random error?
a) Faulty instrument
b) Temperature fluctuations
c) Incorrect setup
d) Worn-out gauge
Answer: b
6. How can gross errors be minimized?
a) Using advanced instruments
b) Operator training

4
 c) Environmental control
d) Reducing precision
Answer: b
7. Which error is repeatable in measurements?
a) Random error
b) Systematic error
c) Gross error
d) Instrumental error
Answer: b
8. Random errors affect measurement:
a) Accuracy
b) Precision
c) Calibration
d) Sensitivity
Answer: b
9. What is an example of a systematic error?
a) Misreading a scale
b) Zero offset in instrument
c) Vibration during measurement
d) Operator fatigue
Answer: b
10. Which error is easiest to detect?
a) Random error
b) Systematic error
c) Gross error
d) Environmental error
Answer: c

3 Length Standards
1. What defines an international standard?
a) Local manufacturing
b) Global acceptance

5
 c) Temporary use
d) Shop floor application
Answer: b
2. Primary standards are used for:
a) Daily inspections
b) Reference calibration
c) Production gauging
d) Material testing
Answer: b
3. Secondary standards are derived from:
a) Working standards
b) Primary standards
c) Shop floor gauges
d) International prototypes
Answer: b
4. Working standards are used in:
a) Laboratory calibration
b) Shop floor measurements
c) International agreements
d) Primary standard creation
Answer: b
5. What is the SI unit of length?
a) Inch
b) Meter
c) Foot
d) Yard
Answer: b
6. Which standard has the highest accuracy?
a) Working standard
b) Secondary standard
c) Primary standard
d) Shop floor standard

6
 Answer: c
7. What material is used for primary standards?
a) Steel
b) Platinum-iridium
c) Aluminum
d) Plastic
Answer: b
8. Working standards are typically:
a) Less accurate
b) More expensive
c) Highly precise
d) Non-portable
Answer: a
9. Which standard is kept in controlled conditions?
a) Working standard
b) Secondary standard
c) Primary standard
d) Shop floor standard
Answer: c
10. What is a feature of secondary standards?
a) Daily use in production
b) Calibration of working standards
c) International prototype
d) Low accuracy
Answer: b

4 Limits, Fits, and Tolerances

1. What does the ISO system standardize?
a) Material properties
b) Fits and tolerances
c) Production rates
d) Inspection methods

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 Answer: b
2. In a hole-basis system, what is fixed?
a) Shaft size
b) Hole size
c) Tolerance range
d) Fit type
Answer: b
3. What does a Go gauge check?
a) Maximum material condition
b) Minimum material condition
c) Surface finish
d) Geometric form
Answer: a
4. A clearance fit ensures:
a) Tight connection
b) Gap between parts
c) Fixed assembly
d) No movement
Answer: b
5. What is tolerance in manufacturing?
a) Material strength
b) Permissible variation
c) Production speed
d) Surface quality
Answer: b
6. In a shaft-basis system, what is constant?
a) Hole size
b) Shaft size
c) Fit type
d) Tolerance limit
Answer: b
7. What does a No-Go gauge verify?

8
 a) Maximum material condition
b) Minimum material condition
c) Surface roughness
d) Part alignment
Answer: b
8. An interference fit results in:
a) Loose connection
b) Tight assembly
c) Free movement
d) Gap formation
Answer: b
9. What defines a transition fit?
a) Always loose
b) Always tight
c) Either clearance or interference
d) No tolerance
Answer: c
10. Which factor affects fit selection?
a) Production cost
b) Assembly requirements
c) Material color
d) Market demand
Answer: b

5 Gauging Techniques
1. What does a plug gauge measure?
a) External diameter
b) Internal diameter
c) Surface finish
d) Flatness
Answer: b
2. A ring gauge is used for:

9
 a) Hole dimensions
b) Shaft dimensions
c) Thread pitch
d) Surface roughness
Answer: b
3. What is a snap gauge designed for?
a) Internal threads
b) External dimensions
c) Surface texture
d) Geometric forms
Answer: b
4. Feeler gauges measure:
a) Hole depth
b) Gap thickness
c) Surface flatness
d) Thread angle
Answer: b
5. Which gauge is used for quick inspection?
a) Plug gauge
b) Vernier caliper
c) Micrometer
d) CMM
Answer: a
6. What is a feature of limit gauges?
a) High precision
b) Go/No-Go assessment
c) Surface measurement
d) Complex setup
Answer: b
7. Which gauge checks thread accuracy?
a) Snap gauge
b) Thread gauge

10
 c) Feeler gauge
d) Ring gauge
Answer: b
8. What material is used for gauges?
a) Plastic
b) Hardened steel
c) Aluminum
d) Wood
Answer: b
9. Which gauge is portable and simple?
a) CMM
b) Feeler gauge
c) Optical comparator
d) Profilometer
Answer: b
10. What is a limitation of plug gauges?
a) High cost
b) Limited to holes
c) Low durability
d) Complex use
Answer: b

6 Comparators
1. What does a mechanical comparator use?
a) Air pressure
b) Gear mechanisms
c) Light beams
d) Electrical signals
Answer: b
2. Optical comparators rely on:
a) Mechanical levers
b) Light projection

11
 c) Air flow
d) Voltage changes
Answer: b
3. Pneumatic comparators measure using:
a) Air pressure
b) Light reflection
c) Gear movement
d) Electrical current
Answer: a
4. Electrical comparators detect:
a) Air flow
b) Voltage variations
c) Light intensity
d) Mechanical force
Answer: b
5. What is a benefit of optical comparators?
a) Low cost
b) High magnification
c) Simple maintenance
d) Portability
Answer: b
6. Which comparator is highly sensitive?
a) Mechanical
b) Pneumatic
c) Optical
d) Electrical
Answer: b
7. What is a drawback of mechanical comparators?
a) High accuracy
b) Wear in parts
c) No maintenance
d) Fast response

12
 Answer: b
8. Pneumatic comparators are ideal for:
a) Rough surfaces
b) Smooth surfaces
c) Large parts
d) Complex shapes
Answer: b
9. Which comparator uses a shadow image?
a) Mechanical
b) Optical
c) Pneumatic
d) Electrical
Answer: b
10. What enhances comparator accuracy?
a) Operator skill
b) Calibration
c) Material type
d) Production speed
Answer: b

7 Metrology in Quality Assurance

1. What is the role of metrology in quality assurance?
a) Increase production speed
b) Ensure product conformity
c) Reduce material costs
d) Simplify design
Answer: b
2. Statistical Process Control (SPC) uses:
a) Random inspections
b) Control charts
c) Manual gauges
d) Visual checks

13
 Answer: b
3. What does inspection verify in QA?
a) Production costs
b) Product specifications
c) Employee performance
d) Market demand
Answer: b
4. SPC helps detect:
a) Process variations
b) Material strength
c) Design flaws
d) Market trends
Answer: a
5. What is a benefit of SPC?
a) Higher defects
b) Reduced waste
c) Increased costs
d) Lower accuracy
Answer: b
6. Which tool monitors process stability?
a) Pareto Chart
b) Control Chart
c) Gantt Chart
d) SWOT Analysis
Answer: b
7. What does acceptance sampling involve?
a) Full inspection
b) Sample testing
c) Process redesign
d) Employee training
Answer: b
8. Metrology in QA ensures:

14
 a) High production speed
b) Dimensional accuracy
c) Material savings
d) Market expansion
Answer: b
9. What does a control chart identify?
a) Material defects
b) Process deviations
c) Employee errors
d) Design changes
Answer: b
10. What improves QA through metrology?
a) Reduced inspections
b) Consistent measurements
c) Higher tolerances
d) Manual processes
Answer: b

8 Measurement of Geometric Forms

1. What does flatness measure?
a) Surface curvature
b) Surface deviation
c) Material thickness
d) Edge alignment
Answer: b
2. Straightness is assessed along:
a) A curved path
b) A linear path
c) A circular path
d) A random path
Answer: b
3. Roundness measures deviation from:

15
 a) A straight line
b) A perfect circle
c) A flat plane
d) A square shape
Answer: b
4. Which tool measures flatness?
a) Vernier caliper
b) Optical flat
c) Feeler gauge
d) Snap gauge
Answer: b
5. What does cylindricity assess?
a) Flat surfaces
b) Cylindrical shapes
c) Angular deviations
d) Surface texture
Answer: b
6. Which instrument measures roundness?
a) Micrometer
b) Roundness tester
c) Plug gauge
d) CMM
Answer: b
7. Straightness is critical for:
a) Decorative parts
b) Machine shafts
c) Flexible components
d) Non-functional surfaces
Answer: b
8. What does parallelism ensure?
a) Curved alignment
b) Equal spacing

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 c) Surface roughness
d) Material strength
Answer: b
9. Which method uses light bands for flatness?
a) Interferometry
b) Micrometry
c) Gauging
d) Profilometry
Answer: a
10. What is a challenge in measuring geometric forms?
a) Low cost
b) High precision needed
c) Simple tools
d) Fast processes
Answer: b

9 Slip Gauges (Johansson Gauges)

1. What is the purpose of slip gauges?
a) Surface finishing
b) Precision measurement
c) Material testing
d) Production speed
Answer: b
2. Wringing of slip gauges involves:
a) Mechanical fastening
b) Adhesive bonding
c) Molecular adhesion
d) Magnetic attachment
Answer: c
3. Slip gauges are classified by:
a) Material type
b) Accuracy grade

17
 c) Production method
d) Surface texture
Answer: b
4. Which material is used for slip gauges?
a) Aluminum
b) Hardened steel
c) Plastic
d) Wood
Answer: b
5. What is a common application of slip gauges?
a) Surface polishing
b) Gauge calibration
c) Material cutting
d) Product assembly
Answer: b
6. Which grade of slip gauge is most accurate?
a) Grade 0
b) Grade 1
c) Grade 2
d) Grade 3
Answer: a
7. Wringing ensures:
a) Loose stacking
b) Tight stacking
c) Random alignment
d) Surface damage
Answer: b
8. Slip gauges are used in:
a) Mass production
b) Precision setups
c) Rough measurements
d) Material testing

18
 Answer: b
9. What is a limitation of slip gauges?
a) High durability
b) Temperature sensitivity
c) Low cost
d) Easy handling
Answer: b
10. Which grade is used for shop floor work?
a) Grade 0
b) Grade 1
c) Grade 2
d) Grade 00
Answer: c

10 Surface Finish Measurement

1. What does CLA measure in surface finish?
a) Peak height
b) Average roughness
c) Total roughness
d) Valley depth
Answer: b
2. RMS in surface finish stands for:
a) Roughness Mean Square
b) Root Mean Square
c) Random Measurement Scale
d) Roughness Magnitude Scale
Answer: b
3. Which parameter denotes average roughness?
a) Rz
b) Ra
c) Rt
d) Rp

19
 Answer: b
4. Rz measures:
a) Average roughness
b) Peak-to-valley height
c) Surface flatness
d) Material strength
Answer: b
5. What does a profilometer assess?
a) Surface texture
b) Material hardness
c) Geometric forms
d) Production speed
Answer: a
6. Which factor affects surface finish?
a) Machining process
b) Operator salary
c) Market demand
d) Product color
Answer: a
7. What is a unit of surface roughness?
a) Newton
b) Micrometer
c) Pascal
d) Joule
Answer: b
8. Which method uses a stylus for measurement?
a) Optical profilometry
b) Contact profilometry
c) Interferometry
d) Visual inspection
Answer: b
9. What does a higher Ra value indicate?

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

11 Coordinate Measuring Machines (CMM)

1. What does a CMM measure?
a) Surface roughness
b) Geometric dimensions
c) Material strength
d) Production speed
Answer: b
2. Which type of CMM uses a gantry?
a) Bridge CMM
b) Cantilever CMM
c) Portable CMM
d) Articulated CMM
Answer: a
3. What is a common CMM probe type?
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. What is a benefit of CMM?
a) Low accuracy
b) High precision
c) High cost
d) Slow measurement
Answer: b
6. Which CMM is suitable for large parts?
a) Portable CMM
b) Bridge CMM
c) Cantilever CMM
d) Articulated CMM
Answer: b
7. What enhances CMM accuracy?
a) Temperature control
b) Manual operation
c) Low-cost probes
d) High vibration
Answer: a
8. Which probe is non-contact in CMM?
a) Touch probe
b) Laser probe
c) Mechanical probe
d) Stylus probe
Answer: b
9. What is a limitation of CMM?
a) High speed
b) High initial cost

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

12 Machine Vision in Metrology

1. What does machine vision enable in metrology?
a) Manual inspection
b) Automated inspection
c) Material testing
d) Production speed
Answer: b
2. 2D vision systems measure:
a) Surface texture
b) Planar dimensions
c) 3D coordinates
d) Material strength
Answer: b
3. 3D vision systems assess:
a) Flat surfaces only
b) Complex geometries
c) Material color
d) Production cost
Answer: b
4. AI in machine vision improves:
a) Manual gauging
b) Defect detection

23
 c) Material cutting
d) Operator training
Answer: b
5. What is a component of vision systems?
a) Air sensor
b) Camera
c) Mechanical lever
d) Plug gauge
Answer: b
6. What is a benefit of machine vision?
a) High cost
b) Fast inspection
c) Low accuracy
d) Complex maintenance
Answer: b
7. Which factor affects vision system accuracy?
a) Lighting conditions
b) Operator salary
c) Material type
d) Market demand
Answer: a
8. Machine vision is ideal for:
a) Low-volume production
b) High-speed inspection
c) Manual measurements
d) Material testing
Answer: b
9. What does AI enhance in vision systems?
a) Mechanical setup
b) Pattern recognition
c) Surface polishing
d) Gauge calibration

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

13 Optical Metrology
1. What does an optical flat measure?
a) Surface roughness
b) Surface flatness
c) Material strength
d) Production speed
Answer: b
2. Interferometry in metrology uses:
a) Air pressure
b) Light waves
c) Mechanical levers
d) Electrical signals
Answer: b
3. What do interference fringes indicate?
a) Surface defects
b) Material thickness
c) Production rate
d) Operator skill
Answer: a
4. Optical flats are made of:
a) Steel
b) Quartz
c) Plastic
d) Aluminum

25
 Answer: b
5. What is a benefit of optical metrology?
a) Low cost
b) High precision
c) Simple setup
d) Slow measurement
Answer: b
6. Which light source is used in interferometry?
a) Incandescent
b) Monochromatic
c) Fluorescent
d) LED
Answer: b
7. What does optical metrology assess?
a) Material strength
b) Surface quality
c) Production cost
d) Employee performance
Answer: b
8. What is a limitation of optical flats?
a) High durability
b) Limited to flat surfaces
c) Low cost
d) Fast measurement
Answer: b
9. Interferometry is used for:
a) Rough surfaces
b) Precision surfaces
c) Large components
d) Flexible materials
Answer: b
10. What enhances optical metrology accuracy?

26
 a) Vibration control
b) High temperature
c) Manual operation
d) Low-cost equipment
Answer: a

14 Laser Interferometry
1. What does laser interferometry measure?
a) Surface roughness
b) Precise distances
c) Material strength
d) Production speed
Answer: b
2. Michelson interferometer uses:
a) Air pressure
b) Laser beams
c) Mechanical gears
d) Electrical signals
Answer: b
3. Twyman-Green interferometer assesses:
a) Surface flatness
b) Material thickness
c) Production rate
d) Operator skill
Answer: a
4. What is a benefit of laser interferometry?
a) Low cost
b) High accuracy
c) Simple setup
d) Slow measurement
Answer: b
5. Laser interferometry is used in:

27
 a) Gauge calibration
b) Material cutting
c) Surface polishing
d) Product assembly
Answer: a
6. What does a laser interferometer detect?
a) Surface texture
b) Interference patterns
c) Material defects
d) Production errors
Answer: b
7. Which factor affects laser interferometry?
a) Air turbulence
b) Operator salary
c) Material color
d) Market demand
Answer: a
8. What is a limitation of laser interferometry?
a) High speed
b) Complex setup
c) Low cost
d) Simple operation
Answer: b
9. Michelson interferometer is used for:
a) Rough surfaces
b) Precision measurements
c) Large components
d) Flexible materials
Answer: b
10. What enhances laser interferometry accuracy?
a) Stable environment
b) Manual operation

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

15 Nano Measurements
1. What does nanometrology study?
a) Macro-scale dimensions
b) Nano-scale dimensions
c) Material strength
d) Production speed
Answer: b
2. AFM stands for:
a) Atomic Force Microscopy
b) Automated Force Measurement
c) Advanced Frequency Modulation
d) Atomic Field Microscopy
Answer: a
3. STM is used to measure:
a) Surface roughness
b) Atomic structures
c) Material thickness
d) Production rate
Answer: b
4. What is a feature of AFM?
a) Low resolution
b) High resolution
c) Large-scale measurement
d) Simple operation
Answer: b
5. Which sensor is used in nanometrology?
a) Air sensor
b) Piezoelectric sensor

29
 c) Mechanical sensor
d) Thermal sensor
Answer: b
6. What is a benefit of STM?
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. What is a limitation of AFM?
a) High speed
b) Small scan area
c) Low cost
d) Simple operation
Answer: b
9. Which factor affects nano measurements?
a) Vibration control
b) Operator salary
c) Material color
d) Market demand
Answer: a
10. What does nanometrology require?
a) Low precision
b) High precision
c) Manual gauges
d) Rough surfaces

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