Which of the following are the main advantages of using a dumpy level? (i) Simple to use (ii) Provides accurate readings (iii) Can be used at night without light
Correct Answer: D. Both (i) and (ii)
📚 Detailed Explanation: Advantages of Dumpy Level Are Simplicity and Accuracy
Why D (Both i and ii) is correct: A dumpy level is a compact, rigid optical instrument. Statements (i) simple to use and (ii) accurate readings are genuine advantages. Statement (iii) “can be used at night without light” is false — the dumpy level is a purely optical telescope instrument requiring visible light to read the staff through the eyepiece.
Evaluation of Each Statement
| Statement | True/False | Explanation |
|---|---|---|
| (i) Simple to use | ✓ TRUE — Advantage | Fewer moving parts than theodolite or tilting level; straightforward setup and operation; ideal for plain levelling work |
| (ii) Provides accurate level readings | ✓ TRUE — Advantage | Rigid telescope with no tilt mechanism eliminates tilt-related errors; stable platform provides consistent readings |
| (iii) Can be used at night without light | ✗ FALSE — NOT an advantage | Dumpy level is a purely optical instrument; requires ambient daylight or artificial illumination to see the staff graduations through the telescope; cannot be used in the dark |
Key Features of Dumpy Level
| Feature | Detail |
|---|---|
| Telescope | Rigidly fixed to levelling head; cannot be tilted or removed |
| Bubble tube | Attached to telescope; must be centred before each reading |
| Suitable terrain | Flat/gently undulating ground; NOT suitable for steep slopes |
| Optical power | High magnification; good for long sight distances on flat terrain |
| Cost | Much less expensive than total stations or digital levels |
- Advantages of dumpy level: simple to use (i) and accurate readings (ii).
- Cannot be used at night without external illumination — optical telescope requires light.
- Best suited for flat terrain; impractical on steep slopes.