what is wave theory?
The wave theory of light says that light is essentially a transverse electromagnetic wave and propagates in space as wavefronts. Wave front construction is done by Huygen's construction under which a point in the primary wavefront acts as a source of the secondary wavefronts. And secondary wavefronts give rise to the next primary wavefront, that is how the wave propagates. It explains refraction, reflection, interference, diffraction and polarization.