what is magnetism? Can an object increase/decrease in magnetism?
In: 2
Magnetism is what you get when electric charges *move*.
So if you run an electric current through a wire, you get a magnetic field. And, if you *change* the magnetic field passing near a wire, that can cause an electric current to start up. That’s the basis of a solid majority of our electrical power generation and transmission: Fuel generates heat, that boils water to get steam, that turns a turbine, that moves strong magnets near wires, that causes an electric current, which can be directed to people’s homes to give us all electrical power. Every electric motor also uses this feature of magnetism.
So, magnetism is what you get when electric charges move. And every single electron in the world is, in a weird sense, “moving”, spinning on some axis, so it has a little magnetic field. On most materials, all these tiny magnetic fields cancel out, but in some (eg, iron), they might not. Iron can be “magnetised” by arranging for (many of) the tiny magnetic fields of the individual atoms to line up and point in the same direction.
And yes, it’s possible to increase or decrease the strength of magnetised iron (or other magnetic materials)
* get a pin or needle (one made of steel), and stroke it with a magnet several times in the same direction – the pin or needle will then become a little magnet, and if you float it on water somehow it will turn to line up with the earth’s magnetic field. Here, the magnetic field you apply induces the mini-magnets within the steel to line up.
* get a magnet, and heat it up enough, and when it cools down, it won’t work as a magnet any more. Here, the heat scrambles the min-magnets in the metal, so they don’t line up any more.
This was, once, the basis of a huge percent of our sound recording industry – a strip of tape coated with very fine iron particles could be “magnetised” with a pattern that represented the sound (or other information) you wanted to record, by imposing a strong magnetic field onto the tape as it rolled by. Then, rolling it by a special device (the “read head”), the tiny magnetic “charges” would induce electric currents in the read head, that would be amplified back to generate the sound.
Latest Answers