AIT Measurement Tools 4 — Questions and Answers
Question 1: A metric vernier caliper main scale reads 23 mm and the vernier scale 11th line aligns. With a least count of 0.02 mm, what is the measurement?
- 23.11 mm
- 23.22 mm (Correct answer)
- 23.02 mm
- 34.00 mm
Correct answer: 23.22 mm
11th vernier line × 0.02 mm = 0.22 mm added to 23 mm gives 23.22 mm.
Question 2: What is the primary advantage of digital calipers over vernier calipers?
- Higher maximum measurement range
- Elimination of parallax error and easier reading (Correct answer)
- Greater durability in harsh environments
- Lower cost
Correct answer: Elimination of parallax error and easier reading
Digital calipers eliminate the need to interpret vernier scales, removing parallax errors and reducing reading mistakes.
Question 3: When measuring with an outside micrometer, what is 'feel' or 'touch' referring to?
- The temperature of the workpiece
- The correct amount of measuring pressure applied through the thimble or ratchet (Correct answer)
- Whether the measuring faces are clean
- The hardness of the material
Correct answer: The correct amount of measuring pressure applied through the thimble or ratchet
Proper measuring feel means applying consistent, light pressure — typically using the ratchet stop to prevent over-tightening.
Question 4: A thickness gauge (feeler gauge) set contains blades of 0.001" to 0.025". To measure a gap of approximately 0.018", which combination is most practical?
- Use only the 0.018" blade if available
- Stack a 0.010" + 0.008" blade
- Use the 0.020" blade alone
- Stack a 0.015" + 0.005" blade (Correct answer)
Correct answer: Stack a 0.015" + 0.005" blade
0.015" + 0.005" = 0.020" — but if 0.018" exists, that's best; otherwise stacking 0.010" + 0.008" = 0.018" is most accurate.
Question 5: In electrical work, a clamp meter measures current by:
- Interrupting the circuit to measure amperage directly
- Sensing the magnetic field produced by current flowing through a conductor (Correct answer)
- Measuring voltage drop across a known resistance
- Counting electron flow per second
Correct answer: Sensing the magnetic field produced by current flowing through a conductor
A clamp meter uses a current transformer (Hall effect or inductive clamp) to sense the magnetic field around a current-carrying conductor.
Question 6: What is the purpose of gauge blocks (Jo blocks) in a machine shop?
- To set cutting tool heights only
- To serve as precision length standards for calibrating and setting other measuring tools (Correct answer)
- To measure surface finish
- To check thread pitch
Correct answer: To serve as precision length standards for calibrating and setting other measuring tools
Gauge blocks are precision ground and lapped to exact sizes, used as reference standards for calibrating measuring instruments.
Question 7: Which tool is used to measure the pitch diameter of an external thread?
- Go/no-go thread ring gauge
- Thread micrometer with V-anvil and cone spindle (Correct answer)
- Outside micrometer with flat faces
- Thread pitch gauge
Correct answer: Thread micrometer with V-anvil and cone spindle
A thread micrometer has a V-shaped anvil and a conical spindle that contact the thread flanks at the pitch diameter.
AIT Measurement Tools 4
A metric vernier caliper main scale reads 23 mm and the vernier scale 11th line aligns.
With a least count of 0.02 mm, what is the measurement?