CHAPTER-8

THEODOLITE

• Q1: Define Theodolite surveying:
  Ans:Theodolite surveying is the system of surveying in which the angles (both horizontal & vertical) are measured with the help of a theodolite.
• Q2: What are the uses of a theodolite?
  Ans:Theodolites are used for measuring horizontal and vertical angles, locating points on a line, prolonging survey lines, setting out grades, and ranging curves.
• Q3: Why a type of theodolite is called a transit theodolite?
  Ans:A theodolite is called a transit theodolite when its telescope can be revolved through a complete revolution about its horizontal axis in the vertical plane.
• Q4: List the essential parts of a theodolite:
  Ans:The essential parts of a theodolite are:

  • ➔ Levelling Head
  • ➔ Shifting Head
  • ➔ Lower Plate
  • ➔ Upper Plate
  • ➔ Plate Levels
  • ➔ Standard (or A Frame)
  • ➔ Vernier Frame
  • ➔ Telescope
  • ➔ Vertical Circle
  • ➔ Altitude Bubble
  • ➔ Tripod Stand
  • ➔ Screws
• Q5: What is levelling head?
  Ans:The levelling head is the lowermost part of a theodolite consisting of two parallel plates separated by levelling screws, providing a means to level the instrument.
• Q6: Define Vernier theodolite.
  Ans: Vernier Theodolite uses verniers to read angles with a least count of 20.
• Q7: Define Micrometer theodolite:
  Ans:Micrometer Theodolite uses a micrometer for angle measurement with a least count of 1.
• Q8: List the essential qualities of a theodolite telescope:
  Ans:

  • ➔ High magnification power
  • ➔ Clear and sharp image formation
  • ➔ Accurate line of sight adjustment
• Q9: What is purpose of Eye-piece?
  Ans:The eyepiece is used for focusing and adjusting the clarity of the image seen through the telescope.
• Q10: What is purpose of Diaphragm?
  Ans:The diaphragm holds the crosshairs or reticles in position to assist in accurate sighting of objects.
• Q11: What is purpose of object glass?
  Ans:The object glass collects and focuses the light to form an image on the crosshair.
• Q12: What are the temporary adjustments of the theodolite?
  Ans:The temporary adjustments of a theodolite include:

  • ➔ Centering
  • ➔ Levelling
  • ➔ Focusing
• Q13: List out the permanent adjustments of Theodolite:
  Ans:The permanent adjustments include:

  • ➔ Adjustment of vertical crosshair
  • ➔ Adjustment of plate level axes
  • ➔ Adjustment of line of sight
  • ➔ Adjustment of horizontal axis
  • ➔ Adjustment of vertical circle index
• Q14: List out the fundamental lines of Theodolite:
  Ans:The fundamental lines include:

  • ➔ The Vertical Axis
  • ➔ The Horizontal Axis
  • ➔ The Line of Collimation
• Q15: Name the two methods of measuring horizontal angles:
  Ans:

  • ➔ Repetition Method
  • ➔ Reiteration Method
• Q16: Define closing error:
  Ans:Closing error is the difference between the sum of measured angles in a traverse and the theoretical sum of angles.
• Q17: Define Easting and Northing:
  Ans:Easting and Northing are coordinate values given by the perpendicular distances from the two main axes in a survey grid.