Story: Magnetic field

Magnetic declination arrow

Magnetic declination arrow

This diagram appears on most topographic maps to show magnetic declination (the difference in angle between grid north and magnetic north). This is the correction that needs to be applied to a magnetic compass reading, to find true north. Grid north runs very close to true north, but because flat maps do not accurately represent curved surfaces, grid north and true north are slightly apart.

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How to cite this page:

Tony Hurst, 'Magnetic field - The magnetic field and its direction', Te Ara - the Encyclopedia of New Zealand, (accessed 5 October 2022)

Story by Tony Hurst, published 12 Jun 2006