Consider a point source of light; the light rays will be diverging from the source. Note that if the source is at infinite or at very large distance the rays will be parallel. For example the Sun's rays are parallel rays. Divergent rays can be made parallel rays by using a convex lens. Refraction of light by a convex lens makes this possible. Let us first understand refraction at a flat surface to begin with.
1. Introduction
Optics is study of behavior of light. Light is actually an electromagnetic wave. The phenomena exhibited by light such as reflection, refraction, dispersion, interference, diffraction and polarization will be studied using rigorous electromagnetic equations at a later stage. Here at the 10th grade level we restrict ourselves to geometric optics i.e. the direction of the wave is traced as a ray to explain the behavior of light.
