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Theodolite Surveying Viva Questions

Theodolite Surveying Viva Questions

1. What you know about axis of the bubble tube?

Axis of the bubble tube it is the straight line that is tangential to the longitudinal curve open of the level tube at its centre. 

2. Explain line of collimation? 

Line of collimation can be defined as the line passing through the intersection of the horizontal and vertical cross hairs and the optical centre of the object glass and its continuation. 

3. What is the optical axis of the telescope? 

Optical axis of the telescope is the line passing through the optical centre of the IPC and the optical centre of the object glass and its continuation. 

4. What is transiting? 

The telescope is turned in vertical plane through 180 degree about the trunnion axis and the process is called transiting.

5. When the telescope is said to be normal? 

If face of the vertical circle is to the left of observer and the level tube is attached to the telescope, then the telescope is said to be normal.

6. Name the axis, in which the telescope and the vertical circle of the theodolite rotate in a vertical plane?

Trunnion axis

7. What is the traverse deflection of angle?

The traverse deflection of angle is the difference between the included angle and 1800.

8. In which traversing, the included angles are measured by setting the vernier near to zero and reads both Vernier on back station?

In precision traverse

9. How will you measure the included angles of a theodolite traversing?

Clockwise direction from the back station

10. Which method is preferred for observing and included angle with better accuracy than what is achievable by a vernier? 

Repetition method. 

11. Which error varies with the direction of pointing and inversely with the length of sight? 

Centering error of a theodolite. 

12. In horizontal angles, which type of error is large for steeply inclined sights? 

The error due to imperfect leveling of the plate bubble. 

13. What can be achieved by focusing the objective and the eyepiece? 

Removal of parallax

14. What type of errors affects the precision of a theodolite traverse in ordinary conditions? 

Systematic linear errors 

15. When angles from two transit stations are preferred? 

If a distant object visible from two transit stations are located, angles from two transit stations are preferred 

16. What is the reliable method of plotting a theodolite traverse? 

By independent coordinates of each station.

17. What is latitude to the leg? 

It is the orthographical projection of a traverse leg upon the reference meridian.

18. What is called as the total latitude? 

Total latitude is the co-ordinate of a point measured perpendicular to the parallel. If the total positive of a point lies north of the reference parallel then it is said to be positive.

19. How the latitude of a traverse leg is obtained? 

By multiplying cosine of its reduced bearing.

20. How balancing the traverse is done if the angular measurements of a traverse are more precise than its linear measurements?


By transit rule 

21. How the length of a traverse leg is obtained? 

Multiply the latitude and secant of its reduced bearing

22. How we can eliminate the error due to defective graduation's on the graduated horizontal circle of a theodolite? 

This can be eliminated by taking the mean of several readings distributed over to different portions of the graduated circle.

23. While traversing, directly or indirectly the measurements are made in the field, these measurements are? 

Linear and angular

24. If the length of a line is multiplied by sine of its reduced the length, what is obtained? 

The departure of a line 

25. Name the instrument with is used for accurately measuring the horizontal and vertical angles? 


26. Discuss about transit theodolite? 

In a vertical plane, if the telescope of a theodolite can revolve through a complete revolution about its it horizontal axis then it is known as transit theodolite.

27. What is the use of theodolite in surveying? 

For finding angles between two lines, finding difference in elevation and prolonging survey line. 

28. How the size of a theodolite is fixed? 

By measuring diameter of the graduated circle of lower plate.

29. Mention the uses of theodolite? 

Finding difference in the elevation, for tunnel aligning and highway ranging.

30.  How the permanent adjustment of the theodolite is attained? 

By the elimination of parallax and by the adjustment of vertical circle index. 

31. How the line of sight of theodolite is adjusted? 

By Spire test 

32. What are the type of errors eliminated my face left and face right observations? 

Eccentricity type errors

33. How the latitude coordinates and departure coordinates are related? 

latitude coordinates - North and South & 

departure coordinates - East and West

34. What you know about consecutive consecutive co-ordinates? 

Consecutive coordinates are the latitude and departure of a station with respect to the preceding station.


35. What type of methods are adopted for balancing consecutive coordinates of a theodolite traverse? 

Transit method, Axis method and Bowditch method.

36. Where the cross hairs are fitted in the surveying telescopes?

In front of the  eyepiece


37. In the surveying telescope diaphragm is nearer to the eyepiece? 


38. Real and inverted images are formed by the objective in the plane of crosshairs? 


39. Name the axis in which the telescope can be rotated in the horizontal plane? 

Vertical axis 

40. The parallax should be removed if the image formed by the objective is not situated in the plane of crosshairs? 


41. The eye-piece should be focused when the crosshairs are not visible clearly? 


42. What is the definition of a telescope? 

The definition of a telescope is the capacity of producing a sharp image. 

43. What you know about the magnification of a telescope? 

The magnification of a telescope is the ratio of focal length of the objective to that of the eyepiece. 

44. What you know about the resolving power of a telescope? 

Resolving power of a telescope is the power to form distinguishable images of objects separated by small angular distance.

45. For the accurate measurement of horizontal angle than a Vernier, which method is used?

Repetition method

46. What you know about the deflection angle? 

Deflection angle is the angle made by a survey line with the prolongation of the p the proceeding line. 

47. What is the range of deflection angle? 

The deflection angle may take any values between 0 degree and 180 degree. 

48. What is a direct angle in surveying? 

The direct angle may be measured clockwise from the proceeding survey line to the following survey line. 

49. What is the range of direct angle? 

The direct angle may take any values between 0 degree and 360 degree. 

50. How Vertical angle is measured? 

The Vertical angle can be measured between the inclined line of sight and the horizontal.

51. Where are the applications of traversing by the method of deflection angles? 

In Highways, railways and canals. 

52. Shifting center is an arrangement provided in theodolite? 


53. What are the parts included in the levelling head of a transit theodolite? 

Parallel plates, Levelling screws and a tribrach plate.


54. What is a scale plate? 

A scale plate is the outer spindle attached to the lower plate in a transit theodolite. 

55. The upper plate is attached to the inner spindle and is called the Vernier plate? 


56. The upper plate is also known as alidade of theodolite? 


57. The upper plate has 2 Vernier 180 degrees apart for reading the horizontal angles? 


58. What are the functions of a levelling head? 

The leveling head is mainly used to attached the theodolite to the tripod, for providing a bearer for the outer hollow spindle and for providing a mean of levelling the instrument. 

59. How the theodolite rotates, when the upper clamp screw is unbolt and the lower clamp screw is stiffened? 

When the lower clamp screw is stiffened and upper clamp screw is unbolt, the theodolite rotates on its inner spindle with relative motion between the graduated scale of lower plate and Vernier. 

60. How you can eliminate the error due to eccentricity of inner and Outer axis? 

This can be eliminated by reading both Vernier and taking the mean of the two observations. 

61. How the error due to line of collimation not being perpendicular to horizontal axis is eliminated? 

This can be eliminated by taking the mean of both face observations.

62. What is the maximum limit of the closing error in a closed traverse?

The maximum limit is √N x least count of instrument

63. What is Relative closing error?

Relative closing error     =   (Closing error) / (Perimeter of the Traverse)

64. What you know about traverse base?

It is the distance between terminal points computed from a subsidiary traverse run between them.

65. What is the direction of closing error, if L is the latitude and D is the departure?

tan θ = ∑D / ∑L

66. What happens to the deflection angle, if the included angle is greater than 180 degrees?

The deflection angle should be right handed or positive.

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