Magnetic Compass: Everything You Need To Know About It

A magnetic compass is a magnetised metal needle positioned in such a way that, it will turn until one end points north and the other points south. You can typically tell about the direction by looking at the Sun’s position in the sky, keeping in mind that the Sun rises in the east and sets in the west. So, if you are looking down on the floating needle at noon, the eye is on the left, the point is on the right. The Sun is somewhere in front of you, you know the needle is pointing north.

The red pointer in a compass (or the magnetised needle on your homemade compass) is a magnet, and it is being attracted by Earth’s inherent magnetism (also known as the geomagnetic field —”geo” simply means “Earth”).

How To Use Magnetic Compass

Compasses that you buy are a little more advanced than floating needles. Though, both work in the same way. Compasses have a lightweight, magnetised pointer that is contained inside a small plastic cylinder filled with liquid. It is positioned on an extremely low-friction pivot. The pointer is printed with the cardinal points of the compass (north, south, east, and west) as well as the intercardinal points on a rectangle of plastic called a compass card (northeast, north-west, south-east, south-west).

To use a compass like this, you must first determine which way is north. Allow the needle to settle before rotating the compass card, so that the needle lines up with the north-south axis and the red end of the needle, marked with an arrow, or printed with the letter ‘N,’ points north. You can then tell if it is south, east, or west, and set out in the direction you need to go (with the help of a map).

How Magnetic Compass Works

Magnetism is one of the first subjects we learn in school, and one of the first concepts we learn is that “like poles repel, unlike poles attract.” To put it another way, if you hold two bar magnets such that their north poles are virtually touching, they will push away from one another. If you turn one of the magnets around, so that the north pole of one magnet is near the south pole of the other magnet, the magnets will pull toward one another.

Earth functions like a giant bar magnet, as English scientist William Gilbert explained about 400 years ago, with one pole up in the Arctic (near the north pole) and the other down in Antarctica (near the south pole). If your compass needle is pointed north, it is being drawn (tugged) toward anything near the north pole of the Earth. 

As opposite poles attract, your compass must be attracted to a magnetic south pole. In other words, the magnetic north pole of Earth is actually the south pole of the magnet inside the planet. This is a perplexing concept, but it will make sense if you remember that opposite poles attract. 

The Earth’s magnetic field is rather weak when compared to the forces that truly control our existence, such as gravity and friction. We must decrease the impacts of these other forces in order for a compass to be able to show up the comparatively little effects of Earth’s magnetism. That is why compass needles are light (so gravity has less of an effect on them), and positioned on frictionless bearings (so the magnetic force has to overcome less frictional resistance).

Base Plate Compass

A vital hiking skill is knowing how to operate a compass. A base plate compass is the traditional hiker’s compass, and it is perfect for any kind of hike or trek. When you are done, wear it around your neck or tuck it inside the pocket of your jacket or daypack. The base plate compass is composed of clear plastic and consists of a magnetic north-facing needle that rotatesly within a circular chamber filled with liquid.

The bezel is a circle that surrounds the chamber and displays the four points of the compass as well as a 360-degree scale. A bearing between two locations or landmarks on a map can be taken using the bezel. This is useful when visibility is low and you know where you are and where you want to go but not which direction to proceed. The distance scales along the sides of a base plate compass can be used to calculate distance on a map, and many such compass models incorporate a magnifier for close examination of map elements.

Thumb Compass

A thumb compass is a smaller and less complicated tool than a base plate compass, making it excellent for trail runners and hikers on well-worn paths. It hooks to the user’s thumb and takes up very little space in a hydration pack, as its name suggests. It is not as complicated as a base plate compass, but it will get you oriented to a map quickly.

Solid State Compass

The solid state compass is popular with sea-going vessels and is present in digital clocks, mobile phones and tablets. It uses magnetic field sensors to feed into a microprocessor that displays data about the device’s orientation.

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