Civil Engineering - Surveying - Discussion

30. 

While viewing through a level telescope and moving the eye slightly, a relative movement occurs between the image of the levelling staff and the cross hairs. The instrument is

[A]. correctly focussed
[B]. not correctly focussed
[C]. said to have parallax
[D]. free from parallax.

Answer: Option C

Explanation:

No answer description available for this question.

Jawad said: (Jun 3, 2016)  
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and it is measured by the angle or semi-angle of inclination between those two lines.

Maratha said: (Jan 21, 2018)  
Give the meaning of free parallax?

Pradip Desai said: (Mar 3, 2018)  
Right @Jawad.

Uday said: (Jul 17, 2020)  
Without any parallax (error) is free parallax or free from parallax.

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