why does a compass needle always point north
If you re lost in the woods, your best chance of finding your way might be a tiny magnet. A magnet is what makes a compass point north -- the small magnetic pin in a compass is suspended so that it can spin freely inside its casing and respond to our planet s magnetism. A compass needle aligns itself and points toward the top of Earth s magnetic field, giving explorers and lost souls a consistent sense of direction. How it works A compass points north because, a north pole and a south pole, and the north pole of one magnet is attracted to the south pole of another magnet. (You may have seen this demonstrated by a pair of simple bar magnets or refrigerator magnets pushed end to end. )
The that can interact with other magnets in this way, so the north end of a compass magnet is drawn to align with the Earth s magnetic field. Because the Earth s magnetic North Pole attracts the north ends of other magnets, it is technically the South Pole of our planet s magnetic field.
True north While a compass is a great tool for navigation, it doesn t always point exactly north. This is because the Earth s magnetic North Pole is not the same as true north, or the Earth s. The magnetic North Pole lies about 1,000 miles south of true north, in Canada. And making things even more difficult for the compass-wielding navigator, the magnetic North Pole isn t even a stationary point. As the Earth s magnetic field changes, the magnetic North Pole moves. Over the last century, it has shifted more than 620 miles (1,000 kilometers) toward Siberia, according to scientists at Oregon State University. This difference between true north and the north heading on a compass is an angle called declination. Declination varies from place to place because the Earth s magnetic field is not uniform it dips and undulates. These local disturbances in the field can cause a compass needle to point away from both the geographic North Pole and the magnetic North Pole.
According to the United States Geological Survey, at, a compass needle can even point south. By using charts of declination or local calibrations, compass users can compensate for these differences and point themselves in the right direction. Got a question? to Life s Little Mysteries and we ll try to answer it. Due to the volume of questions, we unfortunately can t reply individually, but we will publish answers to the most intriguing questions, so check back soon. Wherever on earth we hold a compass, the needle points towards the magnetic North Pole. Compass is widely used in aircrafts, ships, military services, astronomical works and many more to locate directions. Compasses are of many types. A magnetic compass has a magnet that interacts with the earth s magnetic field and aligns itself to point to the magnetic poles. A gyro compass contains a rapidly spinning wheel whose rotation interacts dynamically with the earth s rotation till its axis of rotation is parallel to that of earth s axis.
Whatever be the type, we see that the needle points in the direction of magnetic North Pole. Our planet Earth has got some magnetic field generated deep down inside its core. You are aware of the structure of the earth. The earth has got an inner core, outer core, mantle and an outer crust. The Core is so very hot whose temperature is in the range of 6000 degrees F. Because of the immense pressure exerted on it, the inner core remains a solid mass. The outer core however consists of molten iron due to heat radiating from the core. The causes the movement of molten iron in a rotational pattern. This molten iron in the core acts like a huge bar magnet and the rotational force is supposed to be the cause for magnetic field on the earth s surface. But this field is actually very weak as the surface of earth is very vast. The horizontal component of the earth s magnetic field is in the direction of magnetic north.
This horizontal component pulls a freely suspended magnetized compass towards the magnetic north pole. In other words, a compass detects slight magnetic fields created by any object. To explain why the compass needle points to magnetic north, there is only an assumption theory. It is called the standard bar magnet assumption theory. As per this theory, imagine earth to be having a big bar magnet buried deep inside as shown in the picture. Now the bar magnet s south end is considered to be at the earth s North Pole and north end at earth s South Pole. We know that like poles repel and unlike poles attract. Thus, a freely suspended compass needle points to the earth s magnetic North Pole getting attracted to the south end of the imaginary bar magnet. Compass is also used in the laboratories to detect the small magnetic field produced by a wire carrying a current. How do we apply magnetic field in medical sector? How do door bells work?
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