Levelling MCQ with answer and solution

Concept

Trigonometric levelling finds height differences from vertical angles and distances. It is widely used in geodetic surveys.

Formula

Δh = D tanα + C, where C = 0.0673 D² m (D in km) is the combined curvature and refraction correction

Step-by-step solution

1. Check A: Trigonometric levelling is often used in geodetic (large area) surveys, for example to find heights of triangulation stations. So A is wrong. 2. Check B: Height difference is computed from vertical angle and distance, not read directly. So it is indirect. B is correct. 3. Check C: EDM or total station gives slope distance, and with the vertical angle it gives vertical distance. C is correct. 4. Check D: Curvature makes the far point look lower. Refraction makes it look slightly higher. The net effect is that the measured height difference comes out a little too small, so a correction is added. D is correct. 5. The NOT correct statement is A.

Explanation

Trigonometric levelling is a standard method in geodetic surveys, for example for heights of triangulation stations and mountain peaks. So the statement that it has never been used is false. All the other statements are true.

Why the other options are wrong

B: true, the height difference is found indirectly from angles and distances. C: true, EDM with a vertical angle gives vertical distance. D: true, combined curvature and refraction make the computed vertical value slightly small, so a correction is added.

Shortcut

Words like 'never' or 'always' in a statement often show the false option.

Common mistake

Thinking that geodetic heights come only from spirit levelling.