Light Theories:
Earliest theories of light proposed were to explain the phenomenon of vision rather than the nature of light. Among tactile and emission theories, the latter is more popular and it postulates that the object emits something which enters the eye to form a vision. It is now well established fact that radiations emitted, reflected or scattered by a body are responsible for the visual process
According to the wave theory, light is propagated from one place to another as waves travelling in a hypothetical medium called the ether extending throughout space. Light waves are described in terms of their amplitude, frequency and wave-length (Figure 2-2). Amplitude is the maximum displacement
