The vernier that is calibrated in the direction opposite to the main scale is called ........
📝 Detailed Explanation: The Retrograde Vernier
The key characteristic that defines a retrograde vernier is its calibration direction. Unlike the more common direct vernier, a retrograde vernier has its markings numbered in the opposite direction to the markings on the main scale.
Key Features of a Retrograde Vernier
- Opposite Calibration: The graduations on the vernier scale increase in the opposite direction to the graduations on the main scale.
- Division Length: A single division on the vernier scale is larger than a single division on the main scale.
- Formula: The relationship between the scales is defined as `n` divisions on the vernier scale being equal in total length to `(n+1)` divisions on the main scale.
Because its divisions are larger and it reads "backwards," it can sometimes be considered less intuitive than a direct vernier, but it functions on the same principle of resolving a small difference between two scales.
⚙️ Comparison of Vernier Types
Understanding the differences between vernier types is crucial:
Direct Vernier
The graduations increase in the same direction as the main scale. The formula is `n` VSD = `(n-1)` MSD.
Retrograde Vernier
The graduations increase in the opposite direction to the main scale. The formula is `n` VSD = `(n+1)` MSD.
Extended Vernier
The graduations increase in the same direction, but the divisions on the vernier are much larger than the main scale divisions. The formula is `n` VSD = `(2n-1)` MSD.
Double Vernier
A double vernier is essentially two vernier scales combined (often one direct and one retrograde) that allow for reading in either direction from the index, which is useful on instruments like a surveyor's compass.