. Discuss why external micrometer is more accurate than Vernier in measuring the dimensions. State the accuracy of the micrometer vs the Vernier caliper.
- Discuss why external micrometer is more accurate than Vernier in measuring the dimensions. State the accuracy of the micrometer vs the Vernier caliper.
The Correct Answer and Explanation is:
Answer:
An external micrometer is more accurate than a Vernier caliper due to its design and precision components. The typical accuracy of an external micrometer is ±0.01 mm (0.001 cm), while a Vernier caliper usually has an accuracy of ±0.02 mm (0.002 cm).
Explanation
External micrometers and Vernier calipers are both precision instruments used for measuring the dimensions of objects, particularly external dimensions. However, external micrometers are generally more accurate and are preferred when high precision is required. The reason lies in their construction and the mechanism of measurement.
Micrometers have a finely threaded spindle that moves perpendicularly to the object being measured. The measurement is taken by rotating the thimble, which moves the spindle toward or away from the anvil. The small pitch of the screw thread (usually 0.5 mm per revolution) allows for very fine adjustments and readings. Most standard micrometers can measure with a resolution of 0.01 mm, and higher-precision micrometers can even offer 0.001 mm resolution. This fine resolution makes them highly suitable for tasks that demand a tight tolerance.
On the other hand, Vernier calipers consist of a main scale and a sliding Vernier scale. While they are versatile and can measure internal, external, and depth dimensions, they are not as precise as micrometers due to potential parallax errors, greater user-dependent variability, and the lower resolution of the scale (typically 0.02 mm). The sliding mechanism of the Vernier caliper can also introduce more play or backlash compared to the precision screw of a micrometer.
Additionally, the firm contact between the spindle and anvil in a micrometer reduces uncertainty in measurement, especially when a ratchet or friction thimble is used to apply consistent measuring force. In contrast, inconsistent hand pressure in Vernier calipers can affect readings.
Therefore, due to their mechanical design, precision thread, and consistent measuring force, external micrometers provide more accurate and reliable measurements than Vernier calipers.
