Survey (21-40)

Updated: Apr 8, 2020

21. The main object of running a tie line is to take details of nearby objects

22. Which of the following is an obstacle to chaining but not to ranging ? river

23.A building is an obstacle to both chaining and ranging

24. The main difference between an optical square and a prism square is

that no adjustment is required in a prism square since the angle between

the reflecting surfaces cannot be changed

25.The angle of intersection of the two plane mirrors of an optical square is 45°

26.The allowable length of an offset depends upon the

degree of accuracy required,method of setting out the perpendiculars and nature of ground,scale of plotting

27. Which of the following angles can be set out with the help of French cross staff? either 45° or 90°

28.Which of the following methods of offsets involves less measurement on the ground? method of perpendicular offsets

29.The permissible error in chaining for measurement with chain on rough or hilly

ground is 1 in 250

30.The correction for sag is always subtractive

31.Cross staff is an instrument used for setting out right angles

32.Normal tension is that pull which neutralizes the effect due to pull and

sag

33. Which of the following is not used in measuring perpendicular offsets ?

line ranger

34. If the length of a chain is found to be short on testing, it can be adjusted by

straightening the links

35. The maximum tolerance in a 20 m chain is ±5 mm

36.For accurate work, the steel band should always be used in preference to chain

because the steel band is practically inextensible and is not liable to kinks when in use

37. The length of a chain is measured from outside of one handle to outside of

other handle

38.The true meridian at any place is not variable,The true meridians converge to a

point in northern and southern hemispheres,The maps prepared by national survey departments of any country are based on true meridians.

39. If the true bearing of a line AB is 269° 30', then the azimuth of the line AB is 90° 30'

40. In the prismatic compass the magnetic needle and graduated circle do not move with the box


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