The leveling of instrument is done such that:
(1) Line of sight is truly horizontal
(2) Optical axis is truly horizontal
(3) Vertical axis is truly vertical
(4) Line of collimation is truly horizontal
Answers
optical axis is truly horizontal
Answer: Option 2 is correct genuinely horizontal optical line Then, using the foot fasteners and the instrument's plate levels as a guide, precise leveling is carried out. Leveling is done to make sure that the horizontal line of sight and the vertical plane are actually level.
Explanation: The odolites are permanently adjusted to create a fixed connection between the main lines of the device. The following are the basic axes or lines of a transit theodolite:
Horizontal line
Plate axis values
The telescope's axis
Collimation line
Vertical line
The vernier and axis of height bubble should both display zero.
Once done, these adjustments are durable for a long period. For the instrument's findings to be accurate, these are crucial. In the instance of a transit theodolite, the permanent changes are:
Adjustment of the horizontal line.
The vertical plane and the horizontal line must be parallel.
adjustment of the vertical circular number.
When the line of collimation is horizontal, the vertical circular must display zero.
modifying the height range.
It is necessary for the axis of height to be horizontal to the collimation line.
Collimation correction.
The telescope's axis should be in alignment with the line of collimation or line of sight. The line of sight must also cross the junction of the vertical axis and the horizontal axis perpendicularly. Additionally, the line of sight, ocular axis, and axis of the objective slide should all be in alignment.
adjusting the heights of parallel plates.
Learn more about horizontal line from here;
https://brainly.in/question/2292178
https://brainly.in/question/25632455
#SPJ3