Surveying and Levelling

161. In quadrantal bearing system, back bearing of a line may be obtained from its forward bearing, by

  1. Adding 180°, if the given bearing is less than 180°
  2. Subtracting 180°, if the given bearing, is more than 180°
  3. Changing the cardinal points, i.e. substituting N for S and E for W and vice-versa
  4. None of these

Correct answer: (C)
Changing the cardinal points, i.e. substituting N for S and E for W and vice-versa

162. In reciprocal levelling, the error which is not completely eliminated, is due to

  1. Earth's curvature
  2. Non-adjustment of line of collimation
  3. Refraction
  4. Non-adjustment of the bubble tube

Correct answer: (C)
Refraction

163. In setting up a plane table at any station

  1. Levelling is done first
  2. Centering is done first
  3. Both levelling and centering are done simultaneously
  4. Orientation is done first

Correct answer: (C)
Both levelling and centering are done simultaneously

164. In tacheometrical observations, vertical staff holding is generally preferred to normal staffing, due to

  1. Ease of reduction of observations
  2. Facility of holding
  3. Minimum effect of careless holding on the result
  4. None of these

Correct answer: (C)
Minimum effect of careless holding on the result

165. In tangential tacheometry, an ordinary level staff is used

  1. Leaning towards the instrument for inclined sights upward
  2. Leaning away from the instrument for inclined sights downwards
  3. Vertical in all cases
  4. None of these

Correct answer: (C)
Vertical in all cases

166. In the cross-section method of indirect contouring, the spacing of cross-sections depends upon
(i) Contour interval
(ii) Scale of plan
(iii) Characteristics of ground
The correct answer is

  1. Only (i)
  2. (i) and (ii)
  3. (ii) and (iii)
  4. (i), (ii) and (iii)

Correct answer: (D)
(i), (ii) and (iii)

167. Intersection method of detailed plotting is most suitable for

  1. Forests
  2. Urban areas
  3. Hilly areas
  4. Plains

Correct answer: (C)
Hilly areas

168. It 'θ', is the probable error of an observed bearing of a line of length 'l', the error over the whole length of the traverse of 'n' lines of length 'l' is

  1. l √n
  2. n (θ/l) √n
  3. n θ ∛n
  4. n ⅓ θ√n

Correct answer: (A)
l √n

169. It is more difficult to obtain good results while measuring horizontal distance by stepping

  1. Up-hill
  2. Down-hill
  3. In low undulations
  4. In plane areas

Correct answer: (A)
Up-hill

170. Keeping the instrument height as 1½ m, length of staff 4 m, the up gradient of the ground 1 in 10, the sight on the up slope must be less than

  1. 25 cm
  2. 20 m
  3. 45 m
  4. 10 m

Correct answer: (C)
45 m

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