Section 4: Soil and Water Conservation Engineering
Surveying and Levelling
Subtopic: Instruments for surveying and levelling
Question Statement:
In an optical surveying level, the imaginary line passing through the optical center of the objective lens and the intersection of the crosshairs of the diaphragm is termed the:
Options:
(A) Line of collimation (line of sight)
(B) Axis of the telescope
(C) Vertical axis of the instrument
(D) Axis of the bubble tube
Answer Key:
A
Step-by-Step Solution & Explanation
- Line of collimation: The line joining the intersection of the crosshairs to the optical center of the objective and its continuation.
- Axis of telescope: Line joining the optical centers of the objective and the eyepiece.
- Axis of bubble tube: Tangential line to the longitudinal internal curve of the vial at its center.
Option A is correct.