Fundamental electromagnetic interactions occur between any two particles that have electric charge. These interactions involve the exchange or production of photons. Thus, photons are the carrier particles of electromagnetic interactions.
Electromagnetic decay processes can often be recognized by the fact that they produce one or more photons (also known as gamma particles). They proceed less rapidly than strong decay processes with comparable mass differences, but more rapidly than comparable weak decays.
Forces Within Atoms
Electromagnetic interactions are responsible for the binding force that causes negatively charged electrons to combine with positively charged nuclei to form atoms.
Forces Between Atoms
Residual electromagnetic interactions between electrically neutral atoms are responsible for the binding of atoms to form molecules and most of the forces (apart from gravity) that we experience in everyday life. Molecular binding effects result from atoms sharing and/or exchanging electrons.
The rigidity of the floor supporting you, the friction between your feet and the floor that allows you to walk, the pull of a rubber band on your finger, and the feel of the wind in your faces are all due to residual electromagnetic interactions. Forces such as these result from the changes in energy due to repositioning of electrons or atoms as material is deformed by contact with other material.
Electromagnetic Fields and Electromagnetic Waves
Electromagnetic interactions are also responsible for electric and magnetic field formation around electric charges and electric currents, and for traveling electromagnetic waves such as light, radio-waves, x-rays, and microwaves. All these phenomena are electromagnetic waves and differ only in wavelength.
In the quantum field theory, any changing electromagnetic fields or electromagnetic waves can be described in terms of photons. When there are many photons involved, the effects are equally correct (and more simply) given by the earlier non-quantum theory, namely Maxwell’s equations.
Photons produced in radioactive