What is meant by local attraction? How will you suspect local attraction at the field ? state its effect on included angle.

What is meant by local attraction? How will you suspect local attraction at the field ? state its effect on included angle.
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1 Answer

Answer :

Local attraction: It is the deviation or deflection of magnetic needle from its normal position under influence of external magnetic forces is called as local attraction.


Suspect of local attraction

To suspect the presence of local attraction, the fore and back bearing of a line should be taken. If the difference of the fore and back bearing of a line is exactly 180°, then there is no local attraction.


Effect on included angle

The needle is affected by local attraction therefore it does not give a corrected angle

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Description : State fundamental axis of dumpy level and give their relationship 

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State the important point to be remembered while doing profile leveling.

Description : State the important point to be remembered while doing profile leveling.

Last Answer : 1. The chainage of staff stations are continuous from beginning to the end of the section line. 2. Readings of B.S. and F.S. should be taken very accurately with the bubble exactly in ... their width or by offset. 5)All the temporary adjustments at all instrument position shall carefully be done. 

State different types of leveling. Explain any one in brief.

Description : State different types of leveling. Explain any one in brief.

Last Answer : Types of Levelling  1. Simple Levelling.  2. Differential Levelling.  3. Fly Levelling.  4. Longitudinal or profile leveling.  5. Cross-Section Levelling.  6. Check Levelling.  1. ... B are taken. The difference of these readings gives the difference of level between A and B. 

State different methods of plotting compass traverse.

Description : State different methods of plotting compass traverse. 

Last Answer : Methods of plotting compass traverse are: 1. By parallel meridian through each station. 2. By included angle. 3. By paper protractor. 4. By rectangular co-ordinates. 5. Plotting by tangents. 6. Plotting by chords.

State the procedure to find the foot of the perpendicular on the chain line to take the offset.

Description : State the procedure to find the foot of the perpendicular on the chain line to take the offset. 

Last Answer : Ans: By cross staff 1. The cross staff is held vertically on the chain line where the offset is likely to occur. It is turned until one pair of opposite slits is directed to the ranging rod ( say ... the ranging rod at B. 3. The point P1 vertically under the instruments is required point. 

State the uses of following instruments in survey: i)Cross staff ii) Chain iii) Pegs iv) Arrows

Description : State the uses of following instruments in survey: i)Cross staff ii) Chain iii) Pegs iv) Arrows

Last Answer : i) Cross-Staff: To set up perpendicular or right angle to given chain line OR to find foot of perpendicular from given object to a chain line. ii) Chain: Chains are used for measuring distances. iii) ... on survey lines. iv) Arrows : They are used to mark the end of each chain during chaining. 

State objectives of levelling.

Description : State objectives of levelling.

Last Answer : 1) Obtain the level difference between two points. 2) To find the reduced level of points with respective to mean sea level. 3) To obtain the R.L. with respect to arbitrary bench mark. 4) To establish point on a given RL

State different tapes used based on material of which they are made.

Description : State different tapes used based on material of which they are made. 

Last Answer : Ans:1) Cloth or Linen tape 2) Metallic Tape 3) Steel Tape 4) Invar Tape 5) Fiber Glass wired Tape

State any four classification of surveying based on instrument uesd.

Description : State any four classification of surveying based on instrument uesd. 

Last Answer : i) Chain survey ii) Plane table survey iii) Theodolite survey, iv) Tachometric survey v) compass survey vi) photographic survey, vii) Aerial survey 

State any two uses of Plane Surveying.

Description : State any two uses of Plane Surveying. 

Last Answer : 1) Plane surveying is used for measuring small distance. 2) When area is less than 260 km2, plane survey is normally done. 3) When desired accuracy is less, plane survey is done.

State advantages of Auto-Level over dumpy level.

Description : State advantages of Auto-Level over dumpy level. 

Last Answer : 1) Auto level gives quick and easy leveling with less effort than dumpy level. 2) It is most accurate and precise which gives least error about 0.5 to 0.8 in 5 km. 3) It is simply ... readings to read; which reflects inverted in some dumpy level. 5) It gives more operational comfort to surveyor. 

State sources of error in leveling.

Description : State sources of error in leveling. 

Last Answer : There are three sources of Error a) Instrumental Error :- Imperfect permanent adjustment Sluggish bubble Faulty focusing tube The erroneous leveling staff b) Refraction Error ( error due ... in manipulation  Mistake in reading the rod   Errors in sighting   Mistakes in recording

State merits and demerits of plane table survey.

Description : State merits and demerits of plane table survey. 

Last Answer : Merits: 1) It is the most rapid method of surveying.  2)There is no need for field book as plotting is done along with the field work, so the problem of mistakes in booking field notes does not arise. ... to carry. 5) The map cannot be replotted to defferent scale as there is no field book. 

Explain Fly Levelling with neat sketch. State situation under which fly levelling is needed.

Description : Explain Fly Levelling with neat sketch. State situation under which fly levelling is needed.

Last Answer : Ans: When DifferentialLevelling is done in order to connect a bench mark to the starting point of the alignment of any project, it is called as fly levelling. Fly levelling is also done to connect ...  ii)if distance is more between two points.  iii)if there obstacles between the two points.  

State the different point to be considered in selection of survey station for a closed traverse

Description : State the different point to be considered in selection of survey station for a closed traverse 

Last Answer : 1) Main survey stations should be inter visible. 2) The main survey lines should form well-conditioned triangles. 3) Each triangle or portion of skeleton must be provided with sufficient check lines. ... ) Survey line must be as few as possible so that the frame work can be plotted conveniently.

State the use of alidade in plane table surveying

Description : State the use of alidade in plane table surveying

Last Answer : 1) It is used for sighting the objects to be located.  2) It is used for drawing the rays.