Engineering Principles V11

Clive W. Humphris

OPTICS: Light Propagation.  

Understanding that propagation of light is in straight lines is fundamental to the study of opto-electronics and is especially applicable to the principles of fibre optics. This example clearly shows that the path is straight, but can be blocked.

Light from the source is propagated in every direction and is only directed through reflection. It cannot be cut off, even if a shield is placed in its path as the obstruction just absorbs the energy.

A light ray is an imaginary line which is used to represent the path along which the energy carried by the light wave travels. A beam of light is made up of lots of rays which can be spread out or converged onto a single point. As the energy is directed to a pinpoint it becomes more intense i.e. the light becomes brighter, conversely the light appears dimmed, as its directed over a larger area.

Light waves are humanly visible electromagnetic radiation, forming just a very small part of the full electromagnetic spectrum that ranges from audio frequencies through, radio, infrared, ultraviolet to gamma rays. When all the frequencies in the visible spectrum reach the eye we see white light, otherwise we see a colour.

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