Ray Optics or Geometrical Optics In this optics, the light is considered as a ray which travels in a straight line. It states that for every object, there is an image. Optical instruments are the devices which process light wave to enhance an image for a more clear view. Optical instruments are the tools with which different calculations and measurements of light take place. The ray in optics is used for light propagation and highlighting the path along which the light gets propagated through a medium. The laws of refraction and reflection are valid for all the surfaces and pairs of media at the point of incidences.
Some of the essential terminologies explained in this chapter is given in the bullet points: Refraction, Incident Ray and Refracted, Laws of Reflection and Refraction, Refractive Index, Convex and Concave Mirrors, Transparent and Translucent Medium, Focal plane and Focal length and Principal focus.