Question

The angle between true north and magnetic north is called:

• A. Local attraction
• B. Magnetic declination
• C. Dip of needle
• D. Bearing

Hint:

True Bearing = Magnetic Bearing $\pm$ Declination.
Use (+) for Eastern Declination and (-) for Western Declination when calculating True Bearing.
Remember: "East is Least, West is Best" is a common mnemonic, but for True Bearing, East is Added and West is Subtracted.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
In surveying, there are different meridians used as reference lines.
The "True North" represents the direction towards the geographic North Pole, which remains constant.
The "Magnetic North" is the direction indicated by a freely suspended magnetic needle, which varies due to the Earth's shifting magnetic field.
Step 2: Detailed Explanation:
The horizontal angle between the true meridian (true north) and the magnetic meridian (magnetic north) at a particular location is defined as Magnetic Declination.
1. If the magnetic north is to the east of true north, the declination is termed as "Positive" or "Eastern Declination".
2. If the magnetic north is to the west of true north, the declination is termed as "Negative" or "Western Declination".
- Local attraction refers to the disturbance of the magnetic needle by nearby magnetic objects.
- Dip of the needle is the vertical angle the needle makes with the horizontal plane.
- Bearing is a general term for the horizontal angle between any reference meridian and a line.
Step 3: Final Answer:
The angle between true north and magnetic north is specifically called magnetic declination.