White light shines on a sheet of mica that has a uniform thickness of 1.30 .m. When

Question:

White light shines on a sheet of mica that has a uniform thickness of 1.30 μ.m. When the reflected light is viewed using a spectrometer, it is noted that light with wavelengths of 433.3 nm, 487.5 nm, 557.1 nm, 650.0 nm, and 780.0 nm is not present in the reflected light. What is the index of refraction of the mica?