Levelling MCQ with answer and solution

Concept

Plane surveying ignores the curvature of the earth. So level lines are taken as straight and plumb lines are taken as parallel.

Step-by-step solution

1. Plane surveying ignores the curvature of the earth. 2. Because of this, a level line (a curved line on the real earth) is taken as a straight line. 3. Plumb lines actually meet at the centre of the earth. In plane surveying they are taken as parallel. 4. Answer: straight; parallel, which is option A.

Explanation

In plane surveying the earth's surface is treated as a flat plane. So level lines are straight lines and plumb lines at different points are parallel to each other. In geodetic surveying, level lines are curved and plumb lines meet at the earth's centre.

Why the other options are wrong

B: plumb lines are parallel, not just 'straight'. C: level lines are straight, not 'parallel'. D: the order is reversed.

Shortcut

Plane surveying means a flat earth. Level lines are straight and plumb lines are parallel.

Common mistake

Mixing up the order and choosing D.