# Electromagnetic oscillations and waves

## From vibrations to waves

The comparison of mechanical vibrations and waves (e.g. water waves) and electromagnetic vibrations and waves can be carried out further:

A water wave can be generated in a water basin by a vibrating exciter. This is easy to understand, e.g. in a full bathtub. The water level should be as steady as possible in the initial situation. Now put your finger in the water and move it up and down evenly. Circular waves of water are now spreading from your finger (pathogen).

Analogous to this, an electrical oscillating circuit sends out electromagnetic waves as an exciter. The transmitters of electromagnetic waves are also called antennas and usually have little resemblance to the electrical circuit that we have come to know so far. (Compare the pictures in the introduction.) The antennas described below are in the form of rods and are made of metal.

By the way, there is an important difference between mechanical and electromagnetic waves. Mechanical waves are always bound to a medium in which they can propagate. Water waves propagate in water, sound waves usually in air, but also in liquids and solids - but not in a vacuum. For a long time, physics was unclear about the medium in which electromagnetic waves propagate. It was believed that there was a medium called the ether. However, no one could identify the material properties of this ether, especially since electromagnetic waves also propagate in a vacuum. Today we know that, unlike their mechanical counterparts, electromagnetic waves do not need a medium to propagate. A space in which electromagnetic waves propagate need be filled with nothing more than the electric and magnetic fields that make up the wave. Incidentally, light waves also belong to the electromagnetic spectrum. In this way the light of the most distant stars reaches us through the empty space of the universe.