The most convincing evidence that electromagnetic waves are transverse waves is that they do not require a physical medium for propagation. This means that electromagnetic waves can travel through a vacuum, such as outer space, where there is no air or matter present. Other types of waves, such as sound waves or water waves, require a physical medium, like air or water, to propagate.
Another piece of evidence is that electromagnetic waves can be polarized. Polarization refers to the orientation of the electric field component of the wave. Transverse waves, like electromagnetic waves, have electric and magnetic fields that are perpendicular to the direction of propagation. This allows electromagnetic waves to be polarized, where the electric field oscillates in a specific direction.
Electromagnetic waves also carry energy through space. When an electromagnetic wave travels, it carries both electric and magnetic energy. This energy can be transferred to objects it interacts with, such as heating up an object when exposed to infrared waves.
Furthermore, all electromagnetic waves travel with the same speed through a vacuum, which is the speed of light. This is a fundamental property of electromagnetic waves and is known as the speed of light constant. This constant speed is independent of the wavelength or frequency of the electromagnetic wave.
Lastly, electromagnetic waves can also travel through a material substance. When electromagnetic waves interact with matter, they can be absorbed, reflected, or transmitted. The ability of electromagnetic waves to travel through materials depends on the specific properties of the material, such as its transparency or opacity to different wavelengths of electromagnetic waves.
In summary, the most convincing evidence that electromagnetic waves are transverse waves includes their ability to travel through a vacuum, their polarization characteristics, their ability to carry energy through space, their constant speed through vacuum, and their ability to travel through material substances. These properties all support the conclusion that electromagnetic waves are indeed transverse waves.