Newton's Corpuscular theory described light as particles and that reflection was due to a force that pushed particles that pushed particles away from ths surface. Refraction occured due to corpuscles travelled faster in a denser medium. Huygen's theory described light as waves that every point on a wave can be considered as a point source of secondary wavelets that spread out in the forward direction. The new wavefront is the surface that is tangential to all of the secondary wavelets.
Huygen's Wave theory of light was delayed despite experimental evidence from Young's Double slit experiment due to Newton being an established historical figure as well as Hugen failing to explain double refraction and that he thought light was longitudinal.
The nature of EM waves are such that they have osscilating magnetic and electric fields perpendicular to one another in phase. Hertz discovered radio waves through a spark gap detector and Fizeau determined the speed of light using toothed wheels.
The wave theory of light cannot explain the ultraviolet catstrophe and photoelectric effect. This leads to the particulate model of light.
De Broglie hypothesised that particles each have their associated wavelength known as the De Broglie wavelength. Within eelctron diffraction, diffraction increases as the De Broglie wavelength of electron increases.
Electron microscopes work under the basis of the wave nature of electrons with a De Broglie wavelength similar to the diameter of an atom - 0.1nm. There are 2 types of electron microscopes - Scanning Tunneling Microscope (STM) and Transmission Electron Microscope (TEM).