The ship's compass was useless because of the nearness of the magnetic North Pole.

The relation between electric current, magnetic fields and physical forces was first noted by Hans Christian Ørsted who, in 1820, observed a compass needle was deflected from pointing North when a current flowed in an adjacent wire.

The invention of the magnetic compass, telescope and sextant enabled increasing accuracy.

The advent of magnetic devices, such as the compass and much later, magnetic storage devices, allowed for the creation of far more accurate maps and the ability to store and manipulate them digitally.

As he was setting up his materials, he noticed a compass needle deflected from magnetic north when the electric current from the battery he was using was switched on and off.

One of the most important discoveries relating to current was made accidentally by Hans Christian Ørsted in 1820, when, while preparing a lecture, he witnessed the current in a wire disturbing the needle of a magnetic compass.

The sides of the square base are closely aligned to the four cardinal compass points ( within 4 minutes of arc ) based on true north, not magnetic north, and the finished base was squared to a mean corner error of only 12 seconds of arc.

Given significant distance from the magnetic poles, one can figure which hand is which using a magnetic compass and the sun.

" The ancient Chinese scientist Shen Kuo ( 1031 – 1095 ) was the first person to write of the magnetic needle compass and that it improved the accuracy of navigation by employing the astronomical concept of true north ( Dream Pool Essays, AD 1088 ), and by the 12th century the Chinese were known to use the lodestone compass for navigation.

From his experiments, he concluded that the Earth was itself magnetic and that this was the reason compasses pointed north ( previously, some believed that it was the pole star ( Polaris ) or a large magnetic island on the north pole that attracted the compass ).

Ottoman science and technology had been highly regarded in medieval times, as a result of Ottoman scholars ' synthesis of classical learning with Islamic philosophy and mathematics, and knowledge of such Chinese advances in technology as gunpowder and the magnetic compass.

In China, early versions of the magnetic compass were being developed and used in navigation between 1040 and 1117.

* 1088: the renowned polymath Chinese scientist and official Shen Kuo made the world's first reference to the magnetic compass in his book Dream Pool Essays, along with encyclopedic documentation and inquiry into scientific discoveries.

* A magnetic compass is first used in China.

* Zhu Yu's book is the first to report the use of a magnetic compass for navigation at sea, although the first actual description of the magnetic compass is by another Chinese writer Shen Kuo in his Dream Pool Essays published in 1088.

His book represents the earliest known writing about the magnetic compass, movable type printing, experimentation with the camera obscura only decades after Ibn al-Haytham, and includes many different fields of study in essay and encyclopedic form, including geology, astronomy, botany, zoology, mineralogy, anatomy, pharmacology, geography, optics, economics, military strategy, philosophy, etc.

A simple dry magnetic portable compass.

MRI machines make use of the fact that body tissue contains lots of water, and hence protons ( H < sup >+</ sup > ions ), which get aligned in a large magnetic field.

A magnetic field contains energy, and physical systems move toward configurations with lower energy.

At Earth's orbit its typical density is 6 ions / cm < SUP > 3 </ SUP > ( variable, as is the velocity ), and it contains a variable interplanetary magnetic field ( IMF ) of ( typically ) 2 – 5 nT.

Retrospectively, " networking " of " data " in the Russian language can be traced to the spread of mail and journalism in Russia, and information transfer by technical means came to Russia with the telegraph and radio ( besides, a 1837 sci-fi novel Year 4338, by the 19-century Russian philosopher Vladimir Odoevsky, contains predictions such as " friends ' houses are connected by means of magnetic telegraphs that allow people who live far from each other to talk to each other " and " household journals " " having replaced regular correspondence " with " information about the hosts ’ good or bad health, family news, various thoughts and comments, small inventions, as well as invitations ").

The cassette contains magnetic tape to provide different audio content using the same player.

An example is magnetite ( Fe < sub > 3 </ sub > O < sub > 4 </ sub >), which contains Fe < sup > 2 +</ sup > and Fe < sup > 3 +</ sup > ions with different magnetic moments.

On most modern ATMs, the customer is identified by inserting a plastic ATM card with a magnetic stripe or a plastic smart card with a chip, that contains a unique card number and some security information such as an expiration date or CVVC ( CVV ).

The unconnected magnetic helical field and the material that it contains may violently expand outwards forming a coronal mass ejection.

Magnetic flux is usually measured with a fluxmeter, which contains measuring coils and electronics that evaluates the change of voltage in the measuring coils to calculate the magnetic flux.

Basalt — the iron-rich, volcanic rock making up the ocean floor — contains a strongly magnetic mineral ( magnetite ) and can locally distort compass readings.

This period contains technetium, one of the two elements until lead that has no stable isotopes ( along with promethium ), as well as molybdenum and iodine, two of the heaviest elements with a known biological role, and Niobium has the largest magnetic known penetration depth of all the elements.

This chip contains a radio-frequency electromagnetic field coil that modulates an external magnetic field to transfer a coded identification number when queried by a reader device.

Since the upper atmosphere is not homogeneous and contains significant magnetic structure, the solar ultraviolet ( UV ), EUV and X-ray flux varies markedly in the course of the solar cycle.

The magnetic stripe contains three tracks, each 0. 110 inches ( 2. 79 mm ) wide.

The AAMVA site also contains a list of the Canadian jurisdictions that use magnetic stripes on their driver's licenses.

This implies that the radio-emitting plasma contains, at least, electrons with relativistic speeds ( Lorentz factors of ~ 10 < sup > 4 </ sup >) and magnetic fields.

All the dust contains a magnetic component which was identified as magnetite with some titanium.

The unconnected magnetic helical field and the material that it contains may violently expand outwards forming a CME.

A magnetic monopole implies a mathematical singularity in the vector potential, which can be expressed as a Dirac string of infinitesimal diameter that contains the equivalent of all of the 4πg flux from a monopole " charge " g. The Dirac string starts from, and terminates on, a magnetic monopole.

The analyzer part of the spectrometer contains electric and magnetic fields, which exert forces on ions traveling through these fields.

The head drum usually contains two heads with the magnetic gap of one head slanted slightly leftwards and the magnetic gap of the other head slanted slightly rightwards.

The magnetic field around the wire carrying current to be measured deflects the moving magnet.

A permanent magnet, such as a bar magnet, owes its magnetism to the intrinsic magnetic dipole moment of the electron.

" The dipole moment of the bar magnet points from its magnetic south to its magnetic north pole.

The word is a compound from two Greek terms, ἢλεκτρον, ēlektron, " amber " ( as electrostatic phenomena were first described as properties of amber by the philosopher Thales ), and μαγνήτης, magnētēs, " magnet " ( the magnetic stones found in antiquity in the vicinity of the Greek city of Magnesia, in Lydia, Asia Minor ).

# A current is induced in a loop of wire when it is moved towards or away from a magnetic field, or a magnet is moved towards or away from it, the direction of current depending on that of the movement.

Ørsted did not fully understand his discovery, but he observed the effect was reciprocal: a current exerts a force on a magnet, and a magnetic field exerts a force on a current.

Without magnetic anisotropy, the spins in a magnet randomly change direction in response to thermal fluctuations and the magnet is superparamagnetic.

The domains will remain aligned when the external field is removed, creating a magnetic field of their own extending into the space around the material, thus creating a " permanent " magnet.

The most common stainless steel alloys ( including those used for bolts and nuts ) are not magnetic or only very slightly attracted to a magnet.

An MRI scanner is a device in which the patient lies within a large, powerful magnet where the magnetic field is used to align the magnetization of some atomic nuclei in the body, and radio frequency fields to systematically alter the alignment of this magnetization.

These fields, generated by passing electric currents through gradient coils, make the magnetic field strength vary depending on the position within the magnet.

This magnet creates a very strong magnetic field which varies in uniformity by as much as 40 %.

A second much weaker ( only requiring the electric power necessary to run two hairdryers ) but far more precise magnet then creates a homogeneous magnetic field.

Because the magnetic field is " tuned " by the second magnet, a PMRI scan can be obtained immediately adjacent to a metal prosthetic, unlike an MRI scan.

This aspect of electromagnetic induction is the operating principle behind many electric generators: for example, a rotating bar magnet creates a changing magnetic field, which in turn generates an electric field in a nearby wire.

A magnetic field parallel to the filament is imposed by a permanent magnet.

These magnets are widely used in such products as microphones, professional loudspeakers, in-ear headphones, and computer hard disks, where low magnet mass or volume, or strong magnetic fields are required.

Likewise, due to this high magnetic capacity per weight, neodymium is used in the electric motors of hybrid and electric automobiles, and in the electricity generators of some designs of commercial wind turbines ( only wind turbines with " permanent magnet " generators use neodymium ).

That is, they form a magnet in the presence of a magnetic field — because of the spin magnetic moments of the unpaired electrons in the molecule, and the negative exchange energy between neighboring molecules.

Persistent electric current flows on the surface of the superconductor, acting to exclude the magnetic field of the magnet ( Faraday's law of induction ).

Also, we can see that the LTSC torus maximum diameter is always smaller for a HTSC magnet than LTSC due to higher magnetic field operation.