The Mueller Matrix (MM) elements of the planar liquid crystal cell which is illuminated with a broad band light source was investigated and six MM elements were experimentally measured as functions of wavelength in the range of 500-800 nm at different cell alignment angles. Analysis of the MM curves were used to explain how the state of the linearly polarized light changes at the output of the LC cell. The trends of the MM curves were found to be in agreement with the recent studies on Mueller Stokes characterization of the LC based electro-optical devices. The values at different wavelengths correspond to different phase retardation values, hence it is parallel to changing the cell thickness. It is also found that the state of the polarization ellipse of the travelling light is an important factor that affects the amount of light depolarization.