In an optical square, the angle between the first incident ray and the last reflected ray is ............

In case of a direct vernier scale ............

When the whole circle bearing of a traverse line is between 90° and 180° then ............

The theodolite is an instrument used for measuring very accurately ............

In plate tabling, the instrument used to measure horizontal and vertical distance directly is known as ............

The collimation method for obtaining the reduced levels of points does not provide a check on ............

A surface which is normal to the direction of gravity at all points as indicated by a plumb line is known as ...........…

The sensitiveness of a level tube decreases if ............

Metric chains are generally available in ............