# Civil Engineering - Surveying - Discussion

Discussion Forum : Surveying - Section 2 (Q.No. 49)
49.
A dumpy level is set up with its eye-piece vertically over a peg A. The height from the top of peg A to the centre of the eye-piece is 1.540 m and the reading on peg B is 0.705 m. The level is then setup over B. The height of the eye-piece above peg B is 1.490 m and a reading on A is 2.195 m. The difference in level between A and B is
2.900 m
3.030 m
0.770 m
0.785 m
1.770 m.
Explanation:
No answer description is available. Let's discuss.
Discussion:
10 comments Page 1 of 1.

Vimo said:   4 years ago
Yes, here we can apply the reciprocal levelling formula. Agree @Darshan.

Bharat Chaudhary said:   6 years ago
Yes, right @Suresh @Kashyap.
(1)

Hilly kashyap said:   6 years ago
The true difference of level between A And B is;

e= [(1.540-0.705)+(2.195-1.490)]/2 =0.770.
(4)

Shruti said:   7 years ago

Pusp said:   8 years ago
Average is taken to eliminate an error. Because if there was no error then 0.835 m and 0.705 m would be equal.

Mahesh said:   8 years ago
Yes @Leon.

It is 0.705 m.

Bonnykumar said:   8 years ago
It is a theory of reciprocal levelling.

DARSHAN H A said:   8 years ago
Apply reciprocal leveling formula. Dividing 2 is done to eliminate error due to curvature and refraction.

Leon said:   8 years ago
Can you explain to me why did you divide by 2?

According to me it can either be 0.835 m or 0.705 m?

Suresh Awasthi said:   9 years ago
1. 1.540 m - 0.705 m = 0.835 m.

2. 2.195 m - 1.490 m = 0.705 m.

Now,

Difference in level between A and B = (0.835 + 0.705)/2.

= 0.770 m.
(2)