Symbol help -- Mirrors & units question Calculate to the nearest 0.1000 degree the diffraction angle of the first order image produced by monochromatic light of wavelength 5890.0 A as the light passes through a grating of 5500.0 lines/cm. WHAT DOES THE SYMBOL 'A' MEAN?!?! My guess was 1^-10 but i can't find it on google. So would it be 589nm? Thanks!