---
title: "Define local attraction"
subject: "Surveying I"
chapter: 4
key: "semester_3/surveying_i:define-local-attraction"
source: https://www.bctengineer.com/q/semester_3/surveying_i/define-local-attraction
site: BCT Engineering
---

# Define local attraction

Surveying I · Chapter 4: The Compass

- Asked in: 2081 Baisakh, 1 marks
- Video: [local attraction problem in surveying || compass survey|| survey engineering|| #local_attraction](https://www.youtube.com/watch?v=i_3QTIOjHek) — Aim 2 Civil Class
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/surveying_i/define-local-attraction
- Whole chapter: https://www.bctengineer.com/md/semester_3/surveying_i/chapter-4

## Question

Define local attraction.

## Short answer

Local attraction is the deflection of the magnetic compass needle from the magnetic meridian caused by nearby magnetic materials like iron, steel, electrical cables, or iron-ore deposits. It produces a constant error in all bearings observed at that station.

## Answer

**Local attraction** is the disturbance of the magnetic needle from its normal position (the magnetic meridian) caused by magnetic materials near the station, such as iron or steel objects, electric cables, or iron-ore rocks. It makes the bearings observed at that station wrong by a constant amount.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Local attraction is:
   A. Change of declination over years
   B. Deflection of the needle from the magnetic meridian by nearby magnetic material
   C. Error in chain length
   D. Daily swing of the needle
   Answer: B. Nearby iron or steel disturbs the needle. (Key point: Definition)

2. Which is a likely source of local attraction?
   A. Wooden peg
   B. Plain grass field
   C. Overhead power line or iron object
   D. Ranging rod made of wood
   Answer: C. Iron, steel, electric cables and iron-ore rocks cause it. (Key point: Sources)

3. Bearings at an affected station are wrong by:
   A. A random amount each reading
   B. Zero
   C. 180°
   D. A constant amount
   Answer: D. All bearings at that station have the same error. (Key point: Effect on bearings)

## Related in Surveying I

- [Bearings and local attraction explained](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Abearings-and-local-attraction-terms) — Surveying I, chapter 4, asked 2×
- [Local attraction ABCDEA by included angles](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Alocal-attraction-abcdea-included-angle) — Surveying I, chapter 4, asked 2×
- [Local attraction, bearings AB 305°00′ (EA 45°)](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Alocal-attraction-ea-305-00) — Surveying I, chapter 4, asked 2×
- [Local attraction, bearings AB 305°30′](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Alocal-attraction-ea-bb-44-00) — Surveying I, chapter 4, asked 2×
- [Local attraction: errors and elimination](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Alocal-attraction-sources-elimination) — Surveying I, chapter 4
- [Local attraction in closed traverse PQRSTP](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Alocal-attraction-pqrstp-188-45) — Surveying I, chapter 4