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Unformatted text preview: . The frequencies of light are in
the range of 1015 Hz.
Light spreads in a straight line. A consequence of this statement lies in the formation
of a shadow. A pin sized light source produces a core shadow. In the case of
extended (or several pin sized) light sources, core and half-shadows are
Light beams, which radiate from one point, are divergent (the beam cross-section
increases as the distance grows). Beams which focus on one point are convergent
(the beam cross-section decreases towards the crossover point). Beams without a
common output or point of direction are known as diffuse. 186 © Festo Didactic GmbH & Co. KG • FP 1110 11. Physical fundamentals The speed of light in a vacuum is roughly 300,000 km/s. The table below lists some
values for the speed of light in respect of different materials. Medium v [km/s] Refractive index Vacuum 300,000 1 Air 300,000 1.0003 Water 225,000 1.33 Crown glass (Dependent on type) 198,000 1.51 Flint glass (Dependent on type) 186,000 1...
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- Spring '12