Magnetism is a class of physical attributes that are mediated by magnetic fields. Electric currents and the magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments. Magnetism is one aspect of the combined phenomenon of electromagnetism. The most familiar effects occur in ferromagnetic materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets, producing magnetic fields themselves. Demagnetizing a magnet is also possible. Only a few substances are ferromagnetic; the most common ones are iron, cobalt and nickel and their alloys. The rare-earth metals neodymium and samarium are less common examples. The prefix ferro- refers to iron, because permanent magnetism was first observed in lodestone, a form of natural iron ore called magnetite, Fe3O4.
All substances exhibit some type of magnetism. Magnetic materials are classified according to their bulk susceptibility. Ferromagnetism is responsible for most of the effects of magnetism encountered in everyday life, but there are actually several types of magnetism. Paramagnetic substances, such as aluminum and oxygen, are weakly attracted to an applied magnetic field; diamagnetic substances, such as copper and carbon, are weakly repelled; while antiferromagnetic materials, such as chromium and spin glasses, have a more complex relationship with a magnetic field. The force of a magnet on paramagnetic, diamagnetic, and antiferromagnetic materials is usually too weak to be felt and can be detected only by laboratory instruments, so in everyday life, these substances are often described as non-magnetic.
The magnetic state (or magnetic phase) of a material depends on temperature, pressure, and the applied magnetic field. A material may exhibit more than one form of magnetism as these variables change.
The strength of a magnetic field almost always decreases with distance, though the exact mathematical relationship between strength and distance varies. Different configurations of magnetic moments and electric currents can result in complicated magnetic fields.
Only magnetic dipoles have been observed, although some theories predict the existence of magnetic monopoles.
A long piece of wire with a mass of 0.1kg and a total length of 4m is used to make a square coil with a side of 0.1m. The coil is hinged along a horizontal side, carries a 3.4A current, and is placed in a vertical magnetic field with a magnitude of 0.01T.
a) Determine the angle that the plane...
The magnetic vector potential is given as:
\mathbf{A}(\mathbf{r}) = \frac{\mu _0}{4\pi }\int \frac{\mathbf{J}(\mathbf{r'})}{|\mathbf{r} - \mathbf{r'}|}\d\tau '
I am asked to show that \mathbf{\nabla } \cdot \mathbf{A} = 0 by applying the divergence to the equation above. When I've done...
Hello! I would SOOO appreciate any help I could get with this homework of mine!
I just don't understand and my phys instructor is mean!
Anyway, it's Phys 110, so it should be pretty easy for some of you, but it's hard for me...
Any help would be GREATLY appreciated!
You can IM me...
Questions garanteed to have you doing right handed impressions of rap artists by the end! :smile: :-p
Now I am much happier with electronics, I decided to start reading about magnetics. However, I'd appreciate any help you could provide with a few things I'm thinking about.
First of all...
Hi, I had a thought in my head and was just wondering something.
If I have 2 exact steel balls with the same inital velocity shooting staight up but will one of the balls there is a magnet just above a point where the velocity of that ball will be 0. The steel ball does not come into contact...
Hypothetical experiment:
I have a single 2-inch by 2-inch by 1-inch thick Neodymium magnet affixed on the outer rim of a 1-foot diameter circular hard plastic disk(1/8th-inch). The disk and magnet are held stationary by whatever means.
The underside of the plastic disk has a coating, an...