Difference between revisions of "Beer"
| Line 6: | Line 6: | ||
== 1. The classical law and its history == | == 1. The classical law and its history == | ||
| − | <span style="font-family:Georgia;"> When electromagnetic radiation, such as ultraviolet or visible light, passes through a transparent medium that contains an absorber of that illumination, the radiation’s intensity diminishes steadily with passage through the medium. Commonly the radiation is in the form of a collimated beam that impinges perpendicularly on a slab of width <math>L</math> of the medium, as suggested diagrammatically in Figure 1.One may conjecture that, at any illuminated plane <math>x</math> within the medium, the decrease in the intensity < | + | <span style="font-family:Georgia;"> When electromagnetic radiation, such as ultraviolet or visible light, passes through a transparent medium that contains an absorber of that illumination, the radiation’s intensity diminishes steadily with passage through the medium. Commonly the radiation is in the form of a collimated beam that impinges perpendicularly on a slab of width <math>L</math> of the medium, as suggested diagrammatically in Figure 1.One may conjecture that, at any illuminated plane <math>x</math> within the medium, the decrease in the intensity <math>I</math> of the radiation with distance would be proportional to the uniform concentration <math>c</math> of the absorber and to the local intensity of the light at that point; that is |
<math> | <math> | ||
\frac{\mathrm d}{\mathrm d x} ( I(x) )=-\alpha cI(x) (1) | \frac{\mathrm d}{\mathrm d x} ( I(x) )=-\alpha cI(x) (1) | ||
</math> | </math> | ||
Revision as of 22:15, 3 February 2017
1. The classical law and its history
When electromagnetic radiation, such as ultraviolet or visible light, passes through a transparent medium that contains an absorber of that illumination, the radiation’s intensity diminishes steadily with passage through the medium. Commonly the radiation is in the form of a collimated beam that impinges perpendicularly on a slab of width [math]L[/math] of the medium, as suggested diagrammatically in Figure 1.One may conjecture that, at any illuminated plane [math]x[/math] within the medium, the decrease in the intensity [math]I[/math] of the radiation with distance would be proportional to the uniform concentration [math]c[/math] of the absorber and to the local intensity of the light at that point; that is
[math] \frac{\mathrm d}{\mathrm d x} ( I(x) )=-\alpha cI(x) (1) [/math]
