Wave model and photon model of electromagnetic radiation

The photon model states that: EM waves travel in discrete packets called photons, which have an energy directly proportional to their frequency (E = hf ).

On the other hand, in terms of the wave model, EM radiation can be described as a transverse wave.

Initially, light (which is a type of EM wave) was believed to be composed of tiny particles as this could explain the reflection and refraction of light. However, light was later proved to act as a wave through diffraction experiments, so people believed it was instead formed of waves. Before long, due to the discovery of photoelectricity (explained in 2.392), the attitude towards the composition of light (and EM waves) changed once again. Light had now been proven to act as both a particle and a wave, which led to development of the photon model of light and wave-particle duality.