31 - Light rays

Abstract

This chapter focuses on light rays and its behavior. Light is an electromagnetic wave and the straight line paths followed by narrow beams of light, along which light energy travels, are called rays. Light always travels in straight lines although its direction can be changed by reflection or refraction. The behavior of light rays may be investigated by using a ray-box. This consists merely of a lamp in a box containing a narrow slit that emits rays of light. There are two laws of reflection, namely, the angle of incidence is equal to the angle of reflection and the incident ray, the normal at the point of incidence, and the reflected ray lie in the same plan. When a ray of light passes from one medium to another, the light undergoes a change in direction. This displacement of light rays is called refraction. In general, when entering a denser medium from a less dense medium, light is refracted toward the normal and when it passes from a dense to a less dense medium, it is refracted away from the normal.