My diploma thesis presents the usage of a spectrometer in physics and in optional subjects. The study begins with light spectrum and types of spectrum, the blending of light and colours are described, too. Then the science of spectroscopy and the device called spectrometer are presented. The research work follows and some lighting are shown which are used today and also in classes. The measurements are analyzed and compared with theoretical data. The measurements and analysis are suitable for teaching in 7th and 8th grade of primary school. In addition to analysis the temperature of the Sun and lighting can be calculated. The thesis also proposes the improvements of the measurements and of the device. The usage of spectrometer is absolutely appropriate as a teaching tool and pupils can achieve some of the learning objectives written in the curriculum.