Q46. In a theodolite the line of collimation is:
Difficulty: Medium
A. Parallel to axis of plate levels
B. Parallel to the vertical axis
C. Perpendicular to the trunnion axis
D. Parallel to the horizontal axis
Correct Answer: C. Perpendicular to the trunnion axisSolution:For the telescope to sweep a true vertical plane when tilted, the line of collimation must intersect the trunnion (horizontal) axis at exactly 90°.
Q47. Left swing is not much favoured in theodolite survey, because:
Difficulty: Medium
A. Most surveyors are accustomed to right hand
B. It is inconvenient to turn the telescope anti-clockwise
C. The readings increase clockwise
D. Vertical scale comes to an inconvenient position to be read
Correct Answer: C. The readings increase clockwiseSolution:Horizontal circles are graduated to increase clockwise, matching right swing naturally. Left swing would require reading against this natural direction, increasing error risk.
Q48. In surveying for an area, the instrument Theodolite is used for:
Difficulty: Easy
A. Measurement of vertical distance only
B. Measurement of horizontal angles only
C. Measurement of vertical angles only
D. Measurement of both horizontal and vertical angles
Correct Answer: D. Measurement of both horizontal and vertical anglesSolution:A theodolite’s two separate graduated circles (horizontal and vertical) are exactly what define it, distinguishing it from single-purpose instruments.
Q49. The bubble tube parallel to the telescope of a theodolite should be more sensitive, since it controls:
Difficulty: Medium
A. Vertical axis
B. Horizontal axis
C. Axis of bubble tube
D. None of these
Correct Answer: B. Horizontal axisSolution:This altitude bubble confirms the line of sight is horizontal at the moment of a vertical angle reading — a different job from the plate bubble, which checks the vertical axis.
Q50. The difference between face left and face right observation of a theodolite is 3′. The error is:
Difficulty: Medium
A. 45″
B. 1′ 30″
C. 3′
D. 0
Correct Answer: B. 1′ 30″Solution:The true error is half the FL/FR difference, since the error adds to one face and subtracts from the other equally: 3’/2 = 1’30”.
Q51. The ‘Scale plate’ of a theodolite is:
Difficulty: Easy
A. The upper plate
B. The lower plate
C. Both the above
D. None of the above
Correct Answer: B. The lower plateSolution:The lower plate carries the main 0–360° graduated scale, hence its name “scale plate.” The upper plate carries the vernier and is called the vernier plate.
Q52. The multiplying constant of a theodolite is:
Difficulty: Easy
A. f + d
B. f/d + i
C. f/i + d
D. f/i
Correct Answer: D. f/iSolution:K = f/i is a pure two-variable ratio; it never involves d, which belongs only to the additive constant C = f+d.
Q53. For a tacheometer, the additive and multiplying constants are respectively:
Difficulty: Easy
A. 0 and 0
B. 100 and 100
C. 100 and 0
D. 0 and 100
Correct Answer: D. 0 and 100Solution:An ideal anallactic tacheometer has additive constant C=0 and multiplying constant K=100, giving the simplified formula D=100S.
Q54. The most accurate instrument for measuring horizontal and vertical angles is:
Difficulty: Easy
A. Compass
B. Tape and chain
C. Theodolite
D. Dumpy level
Correct Answer: C. TheodoliteSolution:The theodolite’s fine graduated circles and optical/electronic reading systems give it the finest angular resolution among standard surveying instruments.
Q55. Which method of surveying distance and elevation involves measuring the vertical angle to the graduation on staff using the principle of trigonometry?
Difficulty: Easy
A. Tachometry
B. Triangulation
C. Traversing
D. Trigonometrical
Correct Answer: A. TachometrySolution:Tacheometry combines a vertical angle reading with a staff intercept, applying trigonometric formulas (D=KScos²θ) to find distance and elevation.
Q56. Two distances 200 m and 298 m are measured from a tacheometer instrument and corresponding staff intercepts are 2 m and 3 m respectively. The additive constant will be:
Difficulty: Hard
Correct Answer: A. 4Solution:Subtracting the two equations gives K=98. Substituting back: 200=98(2)+C, so C=200−196=4.
Q57. A method usually adopted to contour rough mountainous regions is:
Difficulty: Medium
A. Chain and compass
B. Chain and level
C. Tacheometry
D. Plane table
Correct Answer: C. TacheometrySolution:Tacheometry determines distance and elevation optically from a single station, avoiding the impractical physical chaining required across rough mountainous ground.
Q58. The main purpose of providing an anallactic lens in a tacheometer is to:
Difficulty: Medium
A. Increase the magnification of the telescope
B. Make the additive constant zero
C. Make the multiplying constant zero
D. Eliminate parallax
Correct Answer: B. Make the additive constant zeroSolution:The anallactic lens optically repositions the effective ray centre to coincide with the instrument’s vertical axis, eliminating the additive constant C entirely.
Q59. When the vertical circle is to the observer’s left and the altitude bubble is up, the telescope is said to be in the:
Difficulty: Easy
A. Face left position
B. Face right position
C. Normal swing position
D. Reversed swing position
Correct Answer: A. Face left positionSolution:“Face left” means the vertical circle is on the observer’s left as they sight the target — conventionally the first (“normal”) observation, before transiting for face right.
Q60. The upper plate (vernier plate) of a theodolite carries the:
Difficulty: Easy
A. Main 0–360° graduated scale
B. Vernier scale and the telescope assembly
C. Magnetic compass needle
D. Foot-screws
Correct Answer: B. Vernier scale and the telescope assemblySolution:The upper plate carries the vernier (fine-reading scale) and mounts the telescope assembly — the lower plate carries the main graduated scale instead.
