11. A Bench Mark (BM) with reduced level (RL) = 155.305 m has been established at the floor of a room. It is required to find out the Rl of the underside of the roof (R) of the room using spirit levelling. The back sight (BS) to the BM has been observed as 1.500 m whereas the fore sight (FS) to R has been observed as 0.575 m (staff held inverted). The RL (m) of R will be
    

1. 1. 155.880
      

   
   
   

   2. 156.230
      

   
   
   

   3. 157.380
      

   
   
   

   4. 157. 860

   
   
   

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1. View Hint View Answer Discuss in Forum

   RL of BM = 155.305      RL = reduced level
   HI = RL of BM + BS        BS = Back sight
     = 155.305 + 1.500
     = 156.805 m
   FS to R = 0.575 (staff inverted)
   ∴ RL = 156.805 + 0.575 = 157.380 m at R

   Correct Option: C

   RL of BM = 155.305      RL = reduced level
   HI = RL of BM + BS        BS = Back sight
     = 155.305 + 1.500
     = 156.805 m
   FS to R = 0.575 (staff inverted)
   ∴ RL = 156.805 + 0.575 = 157.380 m at R

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12. The type of surveying in which the curvature of the earth is taken into account is called
    

1. 1. Geodetic surveying
      

   
   
   

   2. Plane surveying
      

   
   
   

   3. Preliminary surveying
      

   
   
   

   4. Topographical surveying

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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13. Curvature correction to a staff reading in a differential levelling survey is
    

1. 1. always subtractive
      

   
   
   

   2. always zero

   
   
   

   3. always additive

   
   
   

   4. dependent on latitude

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA
   

   Correct Option: A

   NA
   

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14. Determine the correctness or otherwise of the following Assertion (A) and the Reason (R) :
    Assertion (A) : Curvature correction must be applied when the sights are long
    Reason (R) : Line of collimation is not a level line but is tangential to the level line.
    

1. 1. Both (A) and (R) are true and (R) is the correct reason for (A)

   
   
   

   2. Both (A) and (R) are true but (R) is not the correct reason for (a)

   
   
   

   3. Both (A) and (R) are false

   
   
   

   4. (A) is false but (R) is true

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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15. Which of the following errors can be eliminated by reciprocal measurements in differential levelling ?
    I Error due to earth’s curvature
    II Error due to atmospheric refraction
    

1. 1. Both I and II
      

   
   
   

   2. I only
      

   
   
   

   3. II only
      

   
   
   

   4. Neither I nor II

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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