Light falls normally on a transparent diffraction grating of width l = 6.5 cm with 200 lines per millimeter. The spectrum under investigation includes a spectral line with λ = 670.8 nm consisting of two components differing by δλ = 0.015 rim. Find:
(a) In what order of the spectrum these components will be resolved;
(b) The least difference of wavelengths that can be resolved by this grating in a wavelength region λ = 670 nm.