Light Theories

Microscopy Methods in Microbiology
Microroscopy Methods in Microbiology Part 2
Microroscopy Methods in Microbiology - Introduction
Observation of Microbes in the Living State
Observation of Microbes in Smears
Dyes and Staining
Useful pH Range and Colour Change of Some Indicator Dyes
Factors Affecting Staining
Microscopy and Micrometry
Microscopy and Micrometry - Introduction
Behaviour of Light
Light Theories
Resolving Power
Refraction and Reflection
Bright Field Microscopy
Use of Bright Field Microscope

Light Theories

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

Of light path from the position of equilibrium. Frequency of light wave is the number of complete cycles occurring in a second. The property of light waves inversely associated with frequency is the wavelength and is defined as the distance between corresponding points on a wave or distance between two successive peaks or crests. The velocity of lights is estimated as approximately 186,300 miles or 3 x 1010 centimeters per second

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