The deviation of a reading from true North (geographic North) is called

The deviation of a reading from true North (geographic North) is called

• A. Magnetic declination
• B. Magnetic deviation
• C. Variation
• D. Azimuth

Answer: (A)

Magnetic declination is the angle between geographic north (true north) and the direction your compass points (magnetic north) at a specific location. This difference exists because the Earth’s magnetic field isn’t aligned with its geographic poles, and it shifts over time, so the amount of offset varies by place and era. In navigation you convert between magnetic bearings and true bearings by adjusting for this declination: if the declination is east, you add it to the magnetic bearing to get the true bearing; if it’s west, you subtract it. For example, with a 10° east declination, a magnetic bearing of 60° corresponds to a true bearing of 70°. The other terms aren’t what’s being described here: magnetic deviation is local instrument error, variation is an older term sometimes used for the same idea, and azimuth is a general compass or grid bearing, not the offset from true north.

Magnetic declination is the angle between geographic north (true north) and the direction your compass points (magnetic north) at a specific location. This difference exists because the Earth’s magnetic field isn’t aligned with its geographic poles, and it shifts over time, so the amount of offset varies by place and era. In navigation you convert between magnetic bearings and true bearings by adjusting for this declination: if the declination is east, you add it to the magnetic bearing to get the true bearing; if it’s west, you subtract it. For example, with a 10° east declination, a magnetic bearing of 60° corresponds to a true bearing of 70°. The other terms aren’t what’s being described here: magnetic deviation is local instrument error, variation is an older term sometimes used for the same idea, and azimuth is a general compass or grid bearing, not the offset from true north.