SSC JE Civil Engineering 23-Sep-2019 Shift 2 Solved Paper

Question : 108 of 200

Marks: +1, -0

An error due to the earth's curvature and refraction is to be corrected using:

$C_C = 0.0673D^{2}$
$C_C = 0.0112D ^{2}$
$C_C = 0.0136D^{2}$
$C_C = 0.0785D^{2}$

Solution:

Since the effect of curvature is to increase the staff readings and that of refraction is to decrease them and also the effect of curvature is greater than that of refraction, the combined effect is therefore, to increase the staff readings, hence the combined correction is subtractive.
The combined error due to earth's curvature and refraction :
And true staff reading = observed staff reading – 0.0673 D

^{2}

Where, C

_c

= 0.0673 D

^2

The combined correction can be application two ways:
(i) By decreasing each staff reading by the amount 0.0673 D

^2

and then finding, the reduced levels.
(ii) By first finding the reduced levels of the points in the usual way and then increasing them by the amount 0.0673 D

^{2}

Go to Question:

Prev Question

Next Question