The needle and the magnetic poles

What happens if a thin needle enters between the poles of a horseshoe magnet? If you do not have a needle, you can take a thin and light knitting needle or any other lightweight elongated steel object.

What happens if a thin needle enters between the poles of a horseshoe magnet?

The needle would stand vertically. The magnetic field lines pass through the needle, it is magnetized. Then put the needle on the water. Prior to this, it should be greased. The needle will be supported by the surface water film, it does not sink and take a well-defined position: north - south. If the needle is drowning, you need to put it on a piece of cork or foam and let swim in a porcelain cup or mug in aluminum. Thus it is possible to make a simple compass. The needle will show the direction of the magnetic pole.

With the help of a protractor can do the dial, dividing it into 360 degrees with intermediate divisions, or 32 rumba, as is common in marine compasses. With this scale, we can try to measure the so-called magnetic declination in your area.

Earth's magnetic poles do not coincide with its geographic poles. South magnetic pole (in the northern hemisphere) is on the Canadian north, near the island Basterst, in the archipelago of the Queen Elizabeth Islands. Its approximate coordinates - 700 north latitude and 1000 west longitude - are very far from the geographic pole (the coordinates of the approximate because the magnetic poles are constantly moving, "sliding" on the tens kilometers per year). The difference between the directions of the geographic and magnetic poles is called declination.

It is worth mentioning another interesting fact. The sudden reversal of the sample causes it to mechanical vibrations. These vibrations can be heard well in the form of clicks, if on the end of a needle sticking a thin plate of mica and twist the needle in a strong magnetic field.

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