Investigation skills: Magnets

ghostgtr (58)in #technology • 7 years ago

"Look dad, it's magic!" my son said to me one day after returning from school. It was the day they learned about magnets and he finally figured out and understood how all the pictures and letters from school, stuck to the fridge without glue or tape.

In his little mind, it really was magic! That same afternoon, we had to drive to the shops to find him a big magnet just so that he could show me everything that he learned about magnetism.

Magnetism is a class of physical phenomena 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.
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Materials that can be attracted by a magnet are those that have magnetic properties (or power, as my son likes to call it). The first magnetic material to be used was magnetite, a natural metal known as lodestone. Today, magnets are "made" using electricity.

Magnetite/Lodestone

There are three main types of magnets:

Image source

Electromagnets:

When electricity is passed through a coil of wire, a magnetic field appears around the coil. This magnetic field is invisible (like magic)! If a piece of iron is placed inside the coil for a few minutes, it becomes magnetised. When you switch off the electricity, you can take the soft metal out of the coil, and it will now be a new magnet.

The structure of a simple electromagnet

In a solenoid the metal core is free to move in and out of the coil. A solenoid produces linear or straight motion in the core when electricity is passed through the coil. The core can be made to "move in", but reversing the current will not make it move out again.