Question

What is the difference between physical optics and geometrical optics?

Answer 1

Optics is defined as the branch of science which deals with light energy. Light is of dual nature showing both wave properties and particle properties. Physical optics deals with the wave nature of light whereas geometric optics deals with the particle nature of light.

Complete answer:
Light travels in space as electromagnetic waves and also as particles. Let us differentiate between physical optics and geometrical optics.

Physical Optics	Geometrical Optics
Physical optics uses the wave nature of light.	Geometrical optics deals with the particle nature of light.
In physical optics, light is represented as a transverse wave front, like the sinusoidal wave.	In geometrical optics, light is represented as straight lines in a path known as rays.
They are represented with their frequencies and wavelengths being inversely proportional due to the wave speed equation. So, the wave fronts interfere with one another where they intersect.	Light rays are drawn as straight lines originating from a light source and indicating the direction of light. A ray diagram is used to show the paths of several representative light rays as they reflect, refract and transmit through different materials.
It deals with the phenomenon of interference, diffraction, Young’s double slit experiment and many more.	It deals with reflection, refraction, total internal reflection and many more.

Note: It must be noted that the use of geometric optics came to the world long before the physical optics was proposed. Physical optics is also known as wave optics as it considers light as an electromagnetic wave and geometric optics as ray optics as it considers light as a ray.