Magnetic Positive and Negative
Magnetism and electricity are interconnected because they determine the results obtained in many processes, and they share strong similarities. In electricity, the positive and negative charges affect the different observed reactions. In the study of magnets and magnets’ properties, the positive and negative poles are equally important.
The more conventional terms used in describing the poles of a magnet are north and south. The north and south poles behave like positive and negative charges; poles attract and repel one another. As two electric charges induce an electric field, magnetic poles create a magnetic field around them. When comparing the electric field of two or more electric charges to the magnetic field induced by a magnet, the south pole is considered the positive pole, and the north pole is taken as the negative pole.
Magnets are neither positive nor negative. In magnetic therapy, an alternative medicine procedure that uses a magnet as a tool to treat select ailments, magnets are perceived as positive or negative. This is likely a result of the energies associated with these magnets, given that positive energies are preferred to negative ones. However, there are no positive or negative magnets. Learn more about magnetism, magnetic effects, and magnetic fields.
How Magnetism Works
Despite their mutual properties, magnetism and electricity are not the same. In magnetism, unlike in electricity, single magnetic poles do not exist. Magnet poles are usually found as the north and south poles in pairs. Single magnetic poles (monopoles) have been theoretically proposed, but no magnetic monopole has been observed or used in a practical process.
Magnetism studies the fields observed in magnets, as only magnets are capable of inducing and carrying a magnetic field for a long time. In magnetism, the field doesn’t begin at one pole and end at the other but instead exists as a loop that begins from the south pole, leads to the north pole, and returns to the south pole (or from the north pole to the south to the north). Outside a magnet bar, the field goes from north to south, and in the magnet, from south to north.
A magnetic field begins with an unpaired electron existing in the shell of an atom. Electrons have a “spin” capability. That is, they exhibit an angular momentum within an atom. Most electrons spin in pairs in opposite directions, and the cumulative spins cancel out one another for a neutral-charge atom. When an atom has one or more unpaired electrons, the spin effect of the electron is sustained. The direction of this spin determines the direction of the magnetic field induced by the atom. Thus, atoms with multiple unpaired electrons can generate a combined magnetic field observable on a microscopic scale. The magnetic field is measured as Tesla (T), and its symbol is B.
Do you know that the Earth confirms magnetism? The electron spin that causes a magnetic field is likened to the spin of the Earth around its axis. Besides, the Earth has magnetic north and south poles which enable the use of a compass as a traveling guide. The compass’s needle is inclined to the north pole, which corresponds to the Earth’s south magnetic pole (as the south pole attracts the north pole, remember?).
The earliest form of magnetism recorded was ferromagnetism. This was observed in an iron ore known as magnetite. Magnetites are scattered around the Earth, and some of them are magnetized. The magnetized kinds are called lodestones. Since this discovery, other substances have demonstrated strong magnetic fields, including cobalt, nickel, and copper. Neodymium and samarium, rare earth metals, are some of the strongest ferromagnetic substances known.
Magnets that exhibit weak magnetism are known as diamagnetic. Diamagnetism is due to smaller loops created by electrons within an atom. When diamagnetic substances are brought near a material, their magnetic exertions are too weak to be noticed and recorded. When operating in a controlled temperature environment, some diamagnetic substances are stronger than ferromagnetic materials. Pyrolytic carbon shows stronger magnetism, though this is only defined along one axis.
Paramagnetic substances demonstrate temporary magnetic fields. They are substances that become magnetic when brought within a strong magnetic field, reverting to their non-magnetic state when the external field is removed.
Force of Magnetism
The magnetic field force is defined by the Lorentz Force law, which establishes the relationship between magnetism and electricity. The magnetic field is a vector quantity, responding to the direction of the north pole. The expression given for the magnetic Force recognizes that magnetism works in a specific direction at any given time:
F = qv x B
Where F is the magnetic Force applied, q is the charge carried by the electric field, v is the velocity of the charge, and B is a measurement of the magnetic field strength. The equation implies that:
- The Force applied is a product of the velocity and charge and the magnetic field, B, and is perpendicular to the velocity, v, of the charge, q, and the magnetic field.
- The direction of the Force can be observed by studying the right-hand rule (more on that).
The Lorentz force makes particles move at right angles to their inherent directions.
Magnetic Field and Lines of Force
The Force exerted by a magnetic field isn’t a physical property. That is, the human eye cannot observe it. To represent the impact and direction of this Force, curved lines are inscribed relating to the strength of the field. These lines are called lines of Force. This representation gives an insight into the behavior of a magnet. They run from the north pole to the south pole in a continuous loop. The lines of Force indicate the strength of the field. The closer the lines, the stronger the magnet.
The magnetic field line can be visualized by following the right-hand rule. Assuming that for a piece of copper wire held in your right hand, the current runs in the direction of your thumb. If you position your thumb such that it is at a right angle with your second finger, and your middle finger is turned, so it is perpendicular to your thumb, the direction of the middle finger gives you the direction of the magnetic field.
But what if the velocity of the current isn’t parallel to your thumb? There are other ways to determine the magnetic direction of magnetic materials:
Using A Compass
The compass easily shows the direction of a field but doesn’t indicate the strength of the measured field. Wave a compass around a magnetized environment. The needle will indicate the direction of the magnetic field line in the environment. To map out the lines of Force, place multiple compasses within the same environment and plot lines between the dots marked by their different needles.
Using Magnetite or Iron Fillings
These magnetic substances will respond to a magnetic field. The north poles of a small piece of iron will repel the north pole of a magnetic field and attract the south pole. One way to obtain accurate results is to pour the fillings on a piece of paper and drop them from a height. The fillings will bunch together to indicate the lines of Force of a magnetic field. However, they do not indicate the direction of these lines.
Magnetic lines of Force exist in loops. They do not cross one another and bunch together where the magnet is strongest. For any given magnet, the strongest point on the magnet is the core, where the lines are closely packed.
Force of Magnet on A Particle in A Field
Using the right-hand rule, you can visualize the direction of a magnetic field, assuming that the charge acting on the field is a positive charge. For a negative charge, the direction of the field is opposite the direction at which your middle finger points.
If a charge moves parallel to a magnetic field, it exerts no force on the field. For a particle whose charge moves perpendicular to the field, the particle experiences a motion perpendicular to its velocity and changes from a straight-line path to a circular path. If the particle alternates between parallel and perpendicular movements, its path will combine the straight and circular paths, yielding a spiral path. The spiral path is a phenomenon used to study magnetoelectric coupling.
Wrapping It Up
The north and south poles do not reflect the geographical orientation of a magnet or suggest its alignment with the Earth’s north and south poles. They are fitting descriptions for the dipolar features of a magnet, similar to an atom’s positive and negative ions.
Identifying the respective poles helps in magnet storage and preservation and in remagnetizing magnets that have lost partial or total magnetism.
At ROBO Magnetic, we provide long-term counsel on purchasing, using, storing, and preserving magnets. Our expert resources are tailored to help you optimize your magnet sets. Contact us today to get started on your magnet shopping experience.