To read a vernier caliper, follow these steps:
1. Understand the Scales
- The vernier caliper has two scales: the main scale and the vernier scale.
- The main scale provides the main measurement and the first decimal place.
- The vernier scale provides the additional precision, typically the second decimal place or finer, depending on the caliper's least count (e.g., 0.01 cm or 0.02 mm).
2. Take the Main Scale Reading
- Look at the main scale and note the value immediately to the left of the zero mark on the vernier scale.
- This value is your main scale reading.
- For example, if the zero on the vernier scale is between 2.1 cm and 2.2 cm on the main scale, take 2.1 cm as the main scale reading
3. Take the Vernier Scale Reading
- Look along the vernier scale to find the line that best aligns with any line on the main scale.
- The number of this aligned vernier scale line, multiplied by the least count of the vernier scale, gives the vernier scale reading.
- For example, if the 3rd line aligns and each vernier division represents 0.01 cm, the vernier reading is 0.03 cm
4. Calculate the Total Measurement
- Add the main scale reading and the vernier scale reading together:
Total reading=Main scale reading+Vernier scale reading\text{Total reading}=\text{Main scale reading}+\text{Vernier scale reading}Total reading=Main scale reading+Vernier scale reading
- For example, if the main scale reading is 2.1 cm and the vernier scale reading is 0.03 cm, the total measurement is 2.13 cm
Example
- Main scale reading: 1.2 cm (immediately left of zero)
- Vernier scale reading: 0.06 cm (6th vernier line aligns)
- Total measurement: 1.2 cm + 0.06 cm = 1.26 cm
Additional Tips
- Always ensure the caliper jaws are properly closed on the object and the instrument is clean before measuring.
- The smallest reading increment (least count) is often 0.01 cm or 0.02 mm depending on the caliper
- For imperial (inch) vernier calipers, the process is similar but the scales are in inches, often with a least count of 0.001 inches
This method provides precise measurements by combining the coarse main scale reading with the fine vernier scale reading.
