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How does a compass work?
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Quick answer
A compass works because its lightweight magnetic needle is free to rotate and aligns itself with Earth's magnetic field. One end always points toward magnetic north, giving you a reliable sense of direction anywhere on the planet. The needle is a small magnet balanced to spin freely.
Step by step
- The needle is a small magnet balanced to spin freely.
- Earth itself acts like a giant magnet, with field lines running north–south.
- The needle lines up with those lines, pointing to magnetic north.
- Magnetic north differs slightly from true north — a gap called declination.
- Nearby metal or magnets can disturb the reading.
People also ask
Why does a compass point north?
Its magnetized needle aligns with Earth's magnetic field, whose lines run roughly between the magnetic poles, so one end settles pointing north.
Is magnetic north the same as true north?
No. Magnetic north is where the field points; it sits some distance from the geographic North Pole, and the difference is called declination.
Why does metal mess up a compass?
Iron and magnets create their own local fields that pull the needle away from Earth's, giving a false reading.
Is magnetic north the same as the North Pole?
No — magnetic north is near, but not exactly at, the geographic North Pole, and it drifts over time.
What can disturb a compass?
Nearby magnets, metal, or electrical currents can pull the needle off true alignment.
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