For vernier caliper measurements, which scale provides the fractional measurement portion?

• A. Main scale for fractional part
• B. Vernier scale for fractional part
• C. Both scales provide fractional measurements
• D. Vernier scale for the fractional part

Answer: (D)

The way a vernier caliper gives a precise reading is by splitting the measurement into a whole-number part from the main scale and a fine fractional part from the vernier scale. The main scale shows the larger, non-fractional portion of the measurement, giving you the integers (for example, how many millimeters or inches). To obtain the remaining fraction of a unit, you read the vernier scale. Its divisions are slightly smaller than the main scale’s, so when you slide the jaws, one line on the vernier lines up with a line on the main scale. That aligned vernier line corresponds to the fractional amount (like 0.02 mm or 0.001 inch) to add to the main-scale reading. So the fractional measurement portion comes from the vernier scale, which is designed specifically to resolve those small fractions of a unit.