Multiple Choice, Multiple Answers
1 questions. Answer them all, then submit once for your section score.
Read the passage and select ALL correct options. Wrong selections lose points.
Long before satellites and radio beacons, sailors relied on the magnetic compass to find their way across open water. The instrument's needle, aligned with Earth's magnetic field, gave a reliable heading even under overcast skies when the sun and stars were hidden. Yet the compass was never perfectly accurate: magnetic north and true geographic north differ by an angle called declination, which varies by location and shifts slowly over years as Earth's magnetic field changes. Early navigators corrected for this using charts that recorded local declination values, updated periodically by surveyors. Iron cargo and, later, a ship's own steel hull introduced further deviation, requiring correction tables specific to each vessel. Despite these complications, the compass remained the single most important navigational tool for over five centuries.