By attaching a diffraction-grating spectroscope to the astronomical telescope, one can measure the spectral lines from a star and determine the star's chemical composition. Assume the grating has 3500 lines/cm. (a) If the wavelengths of the star's light are 478.5 nm, 647.4 nm, and 696.4 nm, what are the angles at which the first-order spectral lines occur? 478.5 nm line ° 647.4 nm line ° 696.4 nm line ° (b) At what angles are these lines found in the second-order spectrum? 478.5 nm line ° 647.4 nm line ° 696.4 nm line °