It determines the (i) number of lines per meter of the grating and (ii) the wavelengths of the prominent lines (color) of the mercury spectrum using spectrometer. These physical properties can be calculated by knowing four parameters namely number of lines per meter of the grating (N, in m), angle of diffraction (θ, in O), order of the spectrum (m) and wavelength of light used (λ, in m or nm). In that, from these parameters we can calculate the wavelength of the different wavelengths of the prominent lines of the mercury spectrum. The mobile application will be more helpful for students, researchers and scientists for laboratory students.