Question

The variation between the grid north and the true north is called __________.
A. true bearing
B. magnetic declination
C. magnetic variation
D. grid variation

Answer 1

Hint: The variation is a geographical term referring to the northward direction along the grid lines of a map projection. It is a nautical angle at any point on the surface of the earth, between the magnetic and true meridians passing through that point.

Complete answer: Option A: True Bearing is expressed as a horizontal angle between a geographic meridian and a line on the earth surface, especially a horizontal angle measured clockwise from the true north. Therefore, true bearing cannot be the proper answer.
Option B: The term Magnetic North refers to the direction in which the compass needle points, and the angle between Magnetic North and True North is referred to as the magnetic declination. Hence, magnetic declination is not the answer as well.
Option C: Magnetic variation is another term for magnetic declination. Therefore, it also means the angle between magnetic north and true north. Hence, option C, is not the correct answer.
Option D: Grid variation is the nautical angle between grid north and magnetic north at a point on a map or chart. It is the angle at any point on the surface of the earth between the magnetic and true meridians passing through that point. The angle is measured east or west from grid north and is also called a grivation or grid magnetic angle.

Hence, Option D, that says grid variation is the correct answer.

Note: The horizontal angular difference between Grid North and Magnetic North is called the Grid Magnetic Angle. These measurements or angles are very important in navigation.