What describes the difference between magnetic heading and true heading?

• A. Deviation
• B. Variation
• C. Computed visibility
• D. Geographic range

Answer: (B)

The correct answer is variation, which refers specifically to the difference between true north and magnetic north. True heading is based on true north, which is the geographic north pole, while magnetic heading is oriented towards magnetic north, which can differ from true north due to the Earth's magnetic field. Variation accounts for this discrepancy and is expressed in degrees. It can be east or west, indicating how many degrees one must add to or subtract from the magnetic heading to obtain the true heading.

Understanding variation is crucial for navigation, as it helps ensure that the heading used for navigation is accurate relative to the actual geographic direction. This distinction is particularly important when navigating over long distances or in areas where magnetic influences are strong, which can affect the accuracy of a magnetic compass.