--- title: Compasses and the magnetic Earth — a lesson of Mova's school · trees and pragmatics description: «Compasses and the magnetic Earth», a lesson of the physics course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: The whole Earth behaves like a giant magnet, and a compass needle is simply a little magnet free to turn, so it lines up with the Earth's --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/) / Compasses and the magnetic Earth # Compasses and the magnetic Earth Lesson 30 of the physics course of Mova's primary school: 17 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/physics/30-compasses-and-the-magnetic-earth/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/0/) — The whole Earth behaves like a giant magnet, and a compass needle is simply a little magnet free to turn, so it lines up with the Earth's pull and points north. - [1](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/1/) — The Earth's magnetism comes from deep inside, where hot liquid iron swirls in the outer core like a giant dynamo. - [2](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/2/) — The compass points to the magnetic north, which is not quite the same place as the North Pole at the top of the globe. - [3](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/3/) — Put a compass next to a fridge magnet or a steel table and it goes wrong, because the close magnet pulls harder than the far-off Earth. - [4](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/4/) — The Earth's magnetic field also guides charged bits from the Sun down near the poles, where they make the air glow as the northern lights, and many birds can feel the field and use it to find their way. - [5](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/5/) — A compass needle is a small magnet free to turn, and it lines up with the Earth's magnetic field. - [6](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/6/) — A compass points to magnetic north, which is not exactly the same place as the geographic North Pole. - [7](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/7/) — A nearby magnet or piece of steel pulls the needle more strongly than the Earth and makes the compass wrong. - [8](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/8/) — A magnetised needle on a leaf floating in water turns to point north; sailors used compasses like this nearly a thousand years ago. - [9](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/9/) — The Earth's magnetism is made by hot, liquid iron swirling in its outer core. - [10](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/10/) — The Earth's magnetic poles have swapped places many times in its history, over hundreds of thousands of years. - [11](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/11/) — Northern lights happen when charged bits from the Sun are guided by the Earth's magnetism down near the poles and make the high air glow; elsewhere the field shields us from them, and without it, over a very long time, they would strip away some of our air. - [12](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/12/) — Many birds, and also turtles and some fish, can sense the Earth's magnetic field and use it with the Sun and stars to find their way. - [13](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/13/) — A hiker lines up a map with a compass to choose the right path; a compass needs no batteries or phone signal. - [14](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/14/) — The magnetic strip on a bank card stores numbers as patterns of tiny magnetic areas, and a strong magnet can wipe it. - [15](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/15/) — An MRI scanner in hospital uses an extremely strong magnet and radio waves to make pictures of the inside of the body, so metal must stay outside the room. - [16](https://md.mova.elamur.ai/free/en/corpora/school/physics/30-compasses-and-the-magnetic-earth/16/) — A loudspeaker uses electricity in a coil next to a magnet to push a cone in and out, making sound waves in the air. - ← previous: [Magnets: pulling and pushing without touching](https://md.mova.elamur.ai/free/en/corpora/school/physics/29-magnets-pulling-and-pushing-without-touching/) - next →: [Energy: what makes things happen](https://md.mova.elamur.ai/free/en/corpora/school/physics/31-energy-what-makes-things-happen/) - ↑ back to [Physics](https://md.mova.elamur.ai/free/en/corpora/school/physics/)