Abstract
The interactions between matters and electromagnetic radiation plays an important role in chemistry, physics and astronomy. In chemistry, spectroscopy is used by scientists as an alternative method to analyse the properties chemical compound. Spectrometer is an expensive equipment which is commonly used in various field of study. It is used as an instrument to measure the transmittance or reflectance of various liquids and opaque solids. A spectrometer is capable of measuring the ability of chemical substance to absorb light by measuring the intensity of light as a light source passes through a sample chemical substance. Raspberry Pi is a tiny single-board computer which can be fitted into a box along with photo-detecting circuits to build an affordable spectrometer. The Tkinter graphic user interface written in Python displays the output voltage, power and absorbance of light. A Raspberry Pi based spectrometer was developed to measure the ability of chemical substance to absorb light by measuring the power of light as a light source passed through a sample chemical substance. This method can be used to measure the concentration of the soil nutrients in a soil extract. The higher the concentration of the soil nutrients of a soil extract, the higher the light absorbance of a sample. The absorbance of light was computed based on Beer-Lambert Law. The low cost RPI based spectrometer costs 80% less than the spectrometer available in the market and is capable of recording the absorbance measurements up to 5 samples. The performance of this prototype shows that it is possible to build the spectrometer using open-source software and hardware.