Light can work in chloroplast if it is absorbed. Chlorophylls are the substances in chloroplasts that absorb visible light; 380-750 nm in wavelengths. Different pigments of chlorophyll absorb light of different wavelengths and then that are disappearing. An instrument called spectrophotometer is used to measure relative abilities of different wavelengths by chlorophylls.
Only the leaves with help of chlorophyll absorb 1 percent light, the rest is reflected or transmitted. We use spectrophotometric techniques to measure the concentration of light that is absorbed by the chlorophyll in the cuvette. For this we measure the intensity of a light beam after it is directed through and emerges from the chlorophyll in the cuvette. We can gain greater sensitivity by directing different colored light through different types of chlorophyll. For this, we have to isolate the specific wavelengths in the spectrophotometer. This is the reason that a spectrophotometer by striking the light source to the prism, which on separating the light into its component wavelengths, can give us our specific wavelength light. The transmitted light is the light, which has not been absorbed by the chlorophyll in the cuvette. This will strike the phototube in spectrophotometer. The photons of light, which do strike the phototube, will be converted into electrical energy and are measurable by galvanometer.
Only the leaves with help of chlorophyll absorb 1 percent light, the rest is reflected or transmitted. We use spectrophotometric techniques to measure the concentration of light that is absorbed by the chlorophyll in the cuvette. For this we measure the intensity of a light beam after it is directed through and emerges from the chlorophyll in the cuvette. We can gain greater sensitivity by directing different colored light through different types of chlorophyll. For this, we have to isolate the specific wavelengths in the spectrophotometer. This is the reason that a spectrophotometer by striking the light source to the prism, which on separating the light into its component wavelengths, can give us our specific wavelength light. The transmitted light is the light, which has not been absorbed by the chlorophyll in the cuvette. This will strike the phototube in spectrophotometer. The photons of light, which do strike the phototube, will be converted into electrical energy and are measurable by galvanometer.