Magnetic Compass

Magnetic compass is a device which is used to locate the direction of a place. It always rests in a north-south direction and is very helpful as navigators in ships, submarines, aeroplanes.

Magnetic compass, in navigation or surveying, an instrument for determining direction on the surface of Earth by means of a magnetic pointer that aligns itself with Earth’s magnetic field. The magnetic compass is the oldest and most familiar type of compass and is used in different forms in aircraft, ships, and land vehicles and by surveyors.?

Compasses often show angles in degrees: north corresponds to 0°, and the angles increase?clockwise, so east is 90°, south is 180°, and west is 270°. These numbers allow the compass to show?azimuths?or?bearings?which are commonly stated in degrees. If local?variation?between magnetic north and?true north?is known, then direction of magnetic north also gives direction of true north.

Among the?Four Great Inventions, the magnetic compass was first invented as a device for?divination?as early as the?Chinese?Han Dynasty?(since c. 206 BC),and later adopted for navigation by the?Song Dynasty?Chinese during the 11th century.?The first usage of a compass recorded in?Western Europe?and the?Islamic world?occurred around 1190.

The magnetic compass is the most familiar compass type. It functions as a pointer to "magnetic north", the local magnetic meridian, because the?magnetized?needle at its heart aligns itself with the horizontal component of the?Earth's magnetic field. The?magnetic field?exerts a?torque?on the needle, pulling the North end or?pole?of the needle approximately toward the Earth's?North magnetic pole, and pulling the other toward the Earth's?South magnetic pole.?The needle is mounted on a low-friction pivot point, in better compasses a?jewel bearing, so it can turn easily. When the compass is held level, the needle turns until, after a few seconds to allow oscillations to die out, it settles into its equilibrium orientation.