When using a vernier caliper to measure an external diameter, which readings are taken and how are they combined?

When using a vernier caliper to measure an external diameter, which readings are taken and how are they combined?

• A. Read the main scale for whole units
• B. Read the vernier scale for the fractional part
• C. Combine them to obtain the measurement
• D. Ignore the fractional part

Answer: (C)

Measuring an external diameter with a vernier caliper uses two readings that are then combined to get a precise value. Use the outside jaws to grab the object, then read the main scale for the whole-number part. The vernier scale provides the fractional part by pointing to the vernier line that best aligns with a line on the main scale. Add the two readings together to obtain the final measurement, matching the instrument’s least count. For example, if the main scale shows 12.0 mm and the vernier alignment corresponds to 0.38 mm, the measurement is 12.38 mm. This combination is what gives the precise reading beyond what a single scale could provide.

Measuring an external diameter with a vernier caliper uses two readings that are then combined to get a precise value. Use the outside jaws to grab the object, then read the main scale for the whole-number part. The vernier scale provides the fractional part by pointing to the vernier line that best aligns with a line on the main scale. Add the two readings together to obtain the final measurement, matching the instrument’s least count. For example, if the main scale shows 12.0 mm and the vernier alignment corresponds to 0.38 mm, the measurement is 12.38 mm. This combination is what gives the precise reading beyond what a single scale could provide.