Corresponding Author

El-Zomrawy, Adham

Document Type

Original Article

Subject Areas



Spectrophotometr; concentration; kinetic; LDR; LED


A simple, portable photometer depending on the intensity of the light that passes through a colored solution was designed. Through it, the measured light intensity parameter is converted to an electrical current density, which flow in a circuit of light dependent resistor (LDR). The suggested device is characterized by that it does not depend on the absorptivity at a specific wavelength, but depends on the intensity of the light passing through the sample only. The merits of this method are low power, high sensitivity, and very low cost. The proposed method is in excellent harmony with the determination of the concentration of colored solutions by spectrophotometr.

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