🔍 Key Concepts

• Difference between variation and deviation • Meaning of agonic vs isogonic lines on magnetic charts • How lines of equal magnetic variation are shown on isomagnetic charts

💭 Think About

• Ask yourself: what does the word agonic suggest about the amount of variation present? • On an isomagnetic (isogonic) chart, most lines connect points of equal variation. How would a special case of zero variation be shown? • Which choice best matches a line where the magnetic meridian and the geographic meridian are in the same direction?

✅ Before You Answer

• Be clear on what variation is: the angle between true north and magnetic north. • Identify which option describes a condition involving zero variation, not annual change or magnetic latitude. • Confirm that an equator (true or magnetic) is a latitude concept, not directly a variation concept.