Waves are mechanisms for transferring energy by inducing oscillations in the medium through which they propagate, while the medium itself remains in place.

Waves, whether they are sound waves, light waves, or any other type, can be understood as disturbances that travel through a medium. This medium may consist of air, water, or solid materials. It is crucial to recognize that while the wave travels through the medium, the medium itself does not move along with the wave. Instead, the particles of the medium oscillate around fixed points, effectively transferring energy from one particle to the next.

To visualize this process, consider a row of dominoes. When the first domino is knocked over, it strikes the second domino, which then hits the third, and so forth. Although the dominoes remain in their places, the energy from the initial push is transmitted from one domino to the next. Similarly, in a wave, energy is transferred from particle to particle, while the particles themselves oscillate around their equilibrium positions.

In the case of electromagnetic waves, such as light or radio waves, the mechanism differs slightly since these waves can propagate through a vacuum where no particles are present to oscillate. Electromagnetic waves consist of oscillating electric and magnetic fields that generate each other. The energy is carried by the wave as it travels through space, with the oscillating fields transferring energy back and forth between them.

In both scenarios, the essential concept is that a wave represents a disturbance that moves through space, carrying energy with it. The medium—be it air, water, a solid material, or even a vacuum—does not travel with the wave. Rather, the wave prompts the particles of the medium to oscillate, facilitating the transfer of energy from one point to another without necessitating the physical movement of matter. This is how waves effectively transfer energy without displacing matter.

Summary for IB Physics Students: Waves transfer energy by causing the particles of the medium to vibrate around their equilibrium positions, rather than moving the medium itself. For sound or water waves, this means that particles in air or water vibrate but do not propagate with the wave. In contrast, light and radio waves can travel through empty space, with oscillating electric and magnetic fields carrying the energy. Thus, waves are vehicles for energy transfer, not matter.