How can magnets be charged

The force on a negative charge is in exactly the opposite direction to that on a positive charge. Figure 1. Magnetic fields exert forces on moving charges.

This force is one of the most basic known. The direction of the magnetic force on a moving charge is perpendicular to the plane formed by v and B and follows right hand rule—1 RHR-1 as shown. The magnitude of the force is proportional to q, v, B, and the sine of the angle between v and B.

To illustrate this, suppose that in a physics lab you rub a glass rod with silk, placing a nC positive charge on it. The direction of the force is determined with right hand rule 1 as shown in Figure 2. Figure 2. A negative charge moving in the same direction would feel a force straight up. We are given the charge, its velocity, and the magnetic field strength and direction.

Entering the other given quantities yields. This force is completely negligible on any macroscopic object, consistent with experience. The force is perpendicular to the plane formed by v and B. Since the force is zero if v is parallel to B , charged particles often follow magnetic field lines rather than cross them.

Conceptual Questions 1. If a charged particle moves in a straight line through some region of space, can you say that the magnetic field in that region is necessarily zero? What is the direction of the magnetic force on a positive charge that moves as shown in each of the six cases shown in Figure 3? What is the direction of the velocity of a negative charge that experiences the magnetic force shown in each of the three cases in Figure 4, assuming it moves perpendicular to B?

What is the direction of the magnetic field that produces the magnetic force on a positive charge as shown in each of the three cases in the figure below, assuming B is perpendicular to v?

This field surrounds the particle on all sides and instructs other charged particles how to move in response. If a similarly charged particle is nearby, it will be pushed away. If an oppositely charged particle is far away, it will be gently tugged closer. But if you put that electric charge into motion, a surprising thing happens: A new field appears! This strange and exotic field behaves in a strange way: Instead of just pointing straight toward or away from the charge, it twists around it, always perpendicular to the direction of motion.

What's more, a nearby charged particle will only feel this new field if that particle, too, is in motion, and the force it feels is again perpendicular to the direction of its motion.

This field, which for the sake of convenience we'll call the magnetic field, is thus both caused by moving charges and only affects moving charges. But your fridge magnet isn't moving, so what gives? Your magnet itself isn't moving, but the stuff it's made of is. Each and every atom in that magnet has layers and layers of electrons , and electrons are charged particles with a built-in property known as spin. Spin is a fundamentally esoteric and quantum property and the subject of another article , and while it's not technically correct to think of electrons as tiny little spinning metal balls … for the purposes of magnetism, we can think of electrons as tiny little spinning metal balls.

These electrons are charges in motion, and each electron generates its own miniscule magnetic field. In most materials, the different orientations of the electrons cancel out any macroscopic field, but magnets are exactly those kinds of materials where a lot of electrons line up all neat and tidy, making a magnetic field big enough to stick something to your fridge.

Because all the magnetic fields we see in the universe are generated by moving charges, you can never isolate a north and south magnetic pole a "monopole" from each other.

They always come in pairs. If you take a magnet and chop it in half, you just end up with two smaller, weaker magnets — their internal electrons are still whirring about, same as they always were. This property of magnets was and is so well known that James Clerk Maxwell — the dude who figured out that electricity and magnetism are fundamentally connected — simply baked the statement "no such thing as a magnetic monopole" into his equations and left it at that.

And for decades, we had no reason to suspect otherwise, so we let it stand. But as our eyes began to gaze on the weird and wonderful subatomic world, our growing understanding of quantum mechanics put some new wrinkles on that idea. The magnetic compass thus became a tremendous aid to navigation, particularly during the day and at night when the stars were hidden by clouds.

Other metals besides iron have been found to have ferromagnetic properties. These include nickel, cobalt, and some rare earth metals such as samarium or neodymium which are used to make super-strong permanent magnets.

Magnetism takes many other forms, but except for ferromagnetism, they are usually too weak to be observed except by sensitive laboratory instruments or at very low temperatures.

Diamagnetism was first discovered in by Anton Brugnams, who was using permanent magnets in his search for materials containing iron.

Bismuth has been determined to have the strongest diamagnetism of all elements, but as Michael Faraday discovered in , it is a property of all matter to be repelled by a magnetic field. Diamagnetism is caused by the orbital motion of electrons creating tiny current loops, which produce weak magnetic fields, according to HyperPhysics.

When an external magnetic field is applied to a material, these current loops tend to align in such a way as to oppose the applied field. This causes all materials to be repelled by a permanent magnet; however, the resulting force is usually too weak to be noticeable.

There are, however, some notable exceptions. Pyrolytic carbon, a substance similar to graphite, shows even stronger diamagnetism than bismuth, albeit only along one axis, and can actually be levitated above a super-strong rare earth magnet. Certain superconducting materials show even stronger diamagnetism below their critical temperature and so rare-earth magnets can be levitated above them.

In theory, because of their mutual repulsion, one can be levitated above the other. Paramagnetism occurs when a material becomes magnetic temporarily when placed in a magnetic field and reverts to its nonmagnetic state as soon as the external field is removed.

When a magnetic field is applied, some of the unpaired electron spins align themselves with the field and overwhelm the opposite force produced by diamagnetism. However, the effect is only noticeable at very low temperatures, according to Daniel Marsh, a professor of physics at Missouri Southern State University. Other, more complex, forms include antiferromagnetism, in which the magnetic fields of atoms or molecules align next to each other; and spin glass behavior, which involve both ferromagnetic and antiferromagnetic interactions.

Additionally, ferrimagnetism can be thought of as a combination of ferromagnetism and antiferromagnetism due to many similarities shared among them, but it still has its own uniqueness, according to the University of California, Davis.

When a wire is moved in a magnetic field, the field induces a current in the wire. Conversely, a magnetic field is produced by an electric charge in motion. A charge moving in a straight line, as through a straight wire, generates a magnetic field that spirals around the wire.

When that wire is formed into a loop, the field becomes a doughnut shape, or a torus.