The terms "wave" and "unit excitation" refer to different aspects of the electromagnetic field and how it can be described.
A wave typically refers to a propagating disturbance or oscillation that carries energy through space or a medium. In the case of the electromagnetic field, it consists of electric and magnetic fields that oscillate and propagate as electromagnetic waves. These waves can have different frequencies and wavelengths, and they exhibit characteristic properties such as interference, diffraction, and polarization. Electromagnetic waves, including visible light, radio waves, and X-rays, are examples of waves in the electromagnetic field.
On the other hand, a unit excitation, often referred to as a "quantum" or "particle-like" excitation, describes a discrete amount of energy or an elementary particle in the field. In the context of the electromagnetic field, the unit excitation is called a "photon." Photons are quanta of electromagnetic energy and can be thought of as individual particles or discrete packets of light. They have specific energy levels and behave both as particles and as waves, exhibiting properties such as interference and diffraction, similar to waves.
When it comes to describing a proton, it is not accurate to refer to it as a unit excitation of the electromagnetic field. Protons are subatomic particles that belong to a different category than photons. Protons are baryons, specifically hadrons, and are composed of quarks. They have mass and carry a positive charge. Unlike photons, which are excitations of the electromagnetic field, protons are not directly related to the electromagnetic force but are subject to other fundamental forces, such as the strong nuclear force.
In summary, waves in the electromagnetic field describe the propagation of electromagnetic energy, while unit excitations, or photons, are discrete particles or quantized packets of energy in the field. Protons, on the other hand, are subatomic particles with mass and charge, and they are not related to the electromagnetic field in the same way as photons.