The polarization of light and the Malus' law using smartphones
  Originally an empirical law, nowadays Malus' law is seen as a key experiment to demonstrate the transverse nature of electromagnetic waves, as well as the intrinsic connection between optics and electromagnetism. In this work, a simple and inexpensive setup is proposed to quantitatively verify the nature of polarized light. A flat computer screen serves as a source of linear polarized light and a smartphone (possessing ambient light and orientation sensors) is used, thanks to its built-in sensors, to experiment with polarized light and verify the Malus' law. 
Mart\'in Monteiro, Cecilia Stari, Cecilia Cabeza, Arturo C. Marti
physics.ed-ph physics.pop-ph