Questions and answers about ferromagnetic materials
Table of Contents
The difference between "ferromagnetic" and "magnetic"The two terms "ferromagnetic" and "magnetic" are often used as synonyms, but this is not correct. An object is said to be ferromagnetic when a magnet sticks to it. For example, if a magnet adheres to a steel shelf, the shelf is said to be ferromagnetic. Colloquially, this example is incorrectly referred to as a magnetic surface.
Describing an object as magnetic is only correct if it behaves like a magnet.
What ferromagnetic materials do exist? Or: What attracts a magnet?Magnets will only attract objects made of certain materials. The three best-known ferromagnetic elements are:
- Iron (Fe)
- Cobalt (Co)
- and Nickel (Ni)
Some rare earth metals are also ferromagnetic, but only at significantly lower temperatures. At room temperature they are only paramagnetic. This means that they are very weakly attracted by a magnet. These are the following metals:
- Dysprosium (Dy)
- Erbium (Er)
- Gadolinium (Gd)
- Holmium (Ho)
- Terbium (Tb)
Excursus: diamagnetic and paramagnetic substances
Aside from ferromagnetic materials, there are also materials that have diamagnetic or paramagnetic properties. Both diamagnetic and paramagnetic substances are primarily characterised by the fact that they do not stick to magnets. A substance is called diamagnetic when it is very weakly repelled by a magnet. In turn, paramagnetic substances are weakly attracted by magnets.
Are gold or silver ferromagnetic?No, gold and silver are not ferromagnetic - this means that magnets do not attract the two metals. Gold and silver belong to the diamagnetic substances. This means that they are weakly repelled by magnets. Magnets therefore definitely cannot adhere to gold or silver. However, if a magnet sticks to a gold bar, you can assume that the ingot contains impurities of ferromagnetic metals. For that reason, magnets are a practical tool for the authentication of gold and silver.
Our customer project "The gold ingot test" shows in detail how you can test whether gold is genuine or not.
Is aluminium ferromagnetic?
Aluminium is one of the paramagnetic metals. This means that a magnet will only weakly attract it. So weak in fact, that you might think that magnets have no effect on aluminium. However, the video shown here reveals that magnets definitely do have an effect on aluminium.
Incidentally, you will find three exciting experiments with aluminium and magnets in our customer projects:
Is copper ferromagnetic?No, magnets do not stick to copper. Like gold and silver, copper is one of the diamagnetic metals. Magnets therefore weakly repel copper.
Some interesting experiments with copper and magnets can be found in our customer projects: