Grotthus-Draper quantitative law

Under this law a reaction can only be cattsed by radiation if it is absorbed by a molecule. This law reflects the need for interaction between the wave and the molecule. If the absorption of light is necessary, this law is not broad enough because radiation can be absorbed without causing a chemical change. 

The development of photochemistry is actually closely connected to the interpretation of the spectra of light absorption by molecules, which ejqrlairrs whether absorption catrses a chemical change or not. 

qrralitatively it is clear that radiation with greater energy will have a higher chance of causing a reaction, which is to say that in relation [10.73] its frequency is greater or its wavelength is smaller according to [ 10.74]  

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