Section 4: Soil and Water Conservation Engineering
Surveying and Levelling
Subtopic: Instruments for surveying and levelling
Question Statement:
In an optical levelling telescope, the imaginary straight line passing through the optical centre of the objective glass and the intersection of the crosshairs of the reticle is known as the:
Options:
(A) Line of collimation
(B) Axis of the telescope
(C) Axis of the level tube
(D) Vertical axis
Answer Key:
A
Step-by-Step Solution & Explanation
The line of collimation (or line of sight) is defined as the line joining the intersection point of the crosshairs to the optical centre of the objective and its continuation towards the target.