# Surveying Questions and Answers – Photogrammetric Surveying – Photo-Theodolite

This set of Surveying Multiple Choice Questions & Answers (MCQs) focuses on “Photogrammetric Surveying – Photo-Theodolite”.

1. Photo theodolite is a combination of ________________
a) Theodolite, terrestrial camera
b) Electronic theodolite, terrestrial camera
c) Theodolite, aerial camera
d) Electronic theodolite, aerial camera

Explanation: A photo- theodolite is a combination of a terrestrial camera and a theodolite. It involves the usage of obtained photographs for the production of maps with a detailed description. It is able to provide information with utmost accuracy.

2. Focal length of photo theodolite is around _____________
a) 10-20 cm
b) 10-15 cm
c) 15-20 cm
d) 15-30 cm

Explanation: The focal length of photo-theodolite will be around 15-30 cm, which is obtained by placing the lens at certain distance from the eye piece. If at all the lens is placed at other than this distance, it may fail to produce a correct set of observations.

3. Vertical circle provided in the photo theodolite is graduated up to _____________
a) 10 min
b) 30 min
c) 20 min
d) 15 min

Explanation: A vertical frame is mounted with tangent scale is provided, which is pivoted with a magnetic needle having a graduation of 30 minutes. It is one of the basic parts which must be needed so as to produce fine result.

4. The plane perpendicular to the camera axis can be given as ___________
a) Vertical plane
b) Horizontal plane
c) Picture plane
d) Azimuthal plane

Explanation: A picture plane can be given as the plane which is perpendicular to the camera axis at the focal distance in front of the lens. It can be represented as a photograph taken from a film.

5. Which of the following is having the same principle as that of photo-theodolite?
a) Traverse surveying
b) Theodolite surveying
c) Compass surveying
d) Plane-table surveying

Explanation: Photo-theodolite involves the direction of same objects in the photograph by which base is measured is known and positions are located with extremities. It is the same as that of plane table surveying which indicates both are having same principle.
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6. Among the following, which doesn’t belong to the parts of photo-theodolite?
a) Vertical frame
b) Theodolite
c) Rectangular frame
d) Tripod stand

Explanation: A photo-theodolite consists of a camera box with fixed focus, hollow rectangular frame, vertical frame, sensitized photographic plate and a tripod stand. Each of them is having their own importance.

7. Telescope fitted in the photo-theodolite can be rotated in a horizontal plane.
a) False
b) True

Explanation: Telescope fitted in a photo-theodolite is capable of rotating only in a vertical direction but not in any other direction. The plate on which the telescope is fitted can rotate in 360 degrees, by which sighting is possible.

8. The axis of camera passes through ____________
a) Centre of the lens
b) Centre of the axis
c) Centre of the aperture
d) Centre of the camera lens

Explanation: The camera axis provided by the camera fitted on tripod will pass through the centre of the camera lens perpendicular to the camera plate and the picture plate. This will eliminate all imperfections and errors.

9. The formula of focal length used in case of the lens fitted in telescope is given as _____
a) 1/f = 1u – 1/v
b) 1/f = 1u / 1/v
c) 1/f = 1u + 1/v
d) 1/f = 1u * 1/v

Explanation: Focal length of any normal lens can be given as
1/f = 1u + 1/v. here, u and v are the conjugate object and image distances respectively.

10. Which of the following describes the principle point?
a) Intersection of the camera axis with picture plane
b) Intersection of the camera axis with normal plane
c) Intersection of the camera axis with image plane
d) Intersection of the camera axis with plane

Explanation: Principle point is defined as the intersection of the camera axis with a picture plane or the camera plate. Either of them can be chosen based on our availability and the ability to do work.

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