What is the difference between physical optics and geometric optics?

When light is treated as a single beam (A ray) and its properties are studied, as in the case of lenses, mirrors, total internal reflection, rainbow formation, etc., the wavelike properties of light lose significance because the objects we study are much larger than the wavelength of light. This is known as geometric optics.

However, in physical optics, we take into account the wave-like properties of light and develop the more sophisticated concepts based on Huygen's principle. We would deal with Young's double slit experiment and consequently with the characteristic wave-like properties of light interference; we would also deal with polarization and Diffraction, which are also typical wavelike properties; Diffraction occurs only when the size of the obstacle is of the order of the wavelength of light. The wave theory of light was solidified by Maxwell's electromagnetic theory, and it should be noted that physical optics also explains reflection and refraction.

The main distinction was that properties of radiation were discovered in the latter part of the 1800s, which could only be explained by the idea that radiation was made up of discrete energy packets (light is also a form of radiation). Depending on the circumstances, it is therefore best to describe radiation as either a wave or a particle.

Physical optics deals with the wave properties of light and includes phenomena such as interference, diffraction, and polarization. Geometric optics, on the other hand, treats light as rays and focuses on the behavior of light when it interacts with lenses and mirrors, primarily concerned with image formation and properties such as reflection, refraction, and magnification.

Physical optics deals with the wave properties of light, such as interference, diffraction, and polarization, considering light as an electromagnetic wave. Geometric optics, on the other hand, treats light as rays that travel in straight lines and focuses on the behavior of light at boundaries and through optical systems using principles like reflection, refraction, and image formation with lenses and mirrors.