Photons and electromagnetic waves are related but distinct concepts in physics.
Electromagnetic waves refer to the propagation of electric and magnetic fields through space. These waves are formed by oscillating electric and magnetic fields that are perpendicular to each other and also perpendicular to the direction of wave propagation. Electromagnetic waves can be described by various properties such as frequency, wavelength, amplitude, and velocity. Examples of electromagnetic waves include radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Electromagnetic waves are characterized by their wave-like behavior, including properties like interference, diffraction, and polarization.
On the other hand, photons are elementary particles of light and other electromagnetic radiation. Photons are considered the quantum units or quanta of electromagnetic waves. They are massless particles and are the carriers of electromagnetic force. Photons have energy and momentum, and their energy is directly proportional to their frequency. The energy of a single photon is given by the equation E = hf, where E is the energy, h is Planck's constant, and f is the frequency of the photon. Photons also exhibit particle-like behavior, such as being able to be absorbed or emitted by atoms and interacting with matter in discrete packets.
In summary, electromagnetic waves are the overall phenomenon of the propagation of electric and magnetic fields through space, while photons are the individual particles or quanta associated with electromagnetic waves. Electromagnetic waves can be described as continuous wave-like phenomena, while photons are discrete particles that carry energy and momentum.