Question

Discuss the dual nature of electromagnetic waves and how they travel in a vacuum and through a medium.

Answer 1

The dual nature of electromagnetic waves is that they can behave as a wave and also as a particle (a photon). As a wave, when they travel from a vacuum into a medium, the medium causes the light to travel slower (c = 3.00 x 10^8 m/s in a vacuum). The slower speed causes the light to bend, or refract, as it enters the medium.
An example of light acting as a particle is the photoelectric effect. Photons hitting a metal plate will cause electrons to be released, if the photon transfers the right amount of energy.