# Civil Engineering - Surveying - Discussion

Discussion Forum : Surveying - Section 1 (Q.No. 49)
49.
Keeping the instrument height as 1.5 m, length of staff 4 m, the slope of the ground as 1 in 10, the sight on the down-slope, must be less than
30 m
25 m
20 m
15 m
Explanation:
No answer description is available. Let's discuss.
Discussion:
26 comments Page 2 of 3.

BIKAS said:   5 years ago
Thanks @sameer.

But if rising slope then maximum distance measured only 15 meters am I right?

Sagar said:   5 years ago
Thanks @Sameer.

Mamatamayee said:   5 years ago
Thanks @Sameer.

Sameer sopori said:   5 years ago
If we are levelling on the sloped surface then we need to keep staff near the instrument, otherwise, it will not be visible inside the instrument because of the slope (if the distance is more).
so here is the formula, UNDER WHICH DISTANCE WE MUST KEEP STAFF,
Sight= (Staff ht.- instrument ht.)/(1/10)
= (4 - 1.5) /0.1,
= 2.5/0.1,
= 25m.

If you will keep the staff more than 25m away from the instrument , IT WILL NOT BE VISIBLE INSIDE THE INSTRUMENT,
(4)

Avshesh said:   6 years ago
Staff visible= 4-1.5=2.5m,
Site=2.5/(1/10),
= 2.5x10,
= 25m.

Swami said:   7 years ago
Here, 2.5 * 10 = 25.

Ashish tadewar said:   7 years ago
The Hi is 1.5m so when and staff 4m.
The reading will be 2.5m on staff on plane. The slope being 1 in 10.
2.5 * 10 = 25 on down slope.

Doss said:   7 years ago
The instrument height of 1.5m, staff height 4m so 4 - 1.5 = 2.5m.

Justin said:   7 years ago
Please tell me what is the different betwn downslope an upslope.

G mahesh said:   7 years ago
How 2.5 came?