Two sources S1 and S2 aligned vertically emit polarized waves whose electric fields are perpendicular to the plane of the sheet and come out. The intensities are respectively: I1 = 200 W/m2 and I2 = 150 W/m2. The signal coming from source S1 crosses an interface to interfere at point P with the other signal coming from source S2. The wavelength in vacuum is ?0=1 m.