mλ=d·sinθm
where λ is the wavelength of the spectral line being observed, d is the groove spacing of the diffraction grating, m is the order of the spectrum, θm is the corresponding angle at which the mth order spectrum is observed. The 1st order (m = 1)
occurs at the smallest angle with respect to 90o to the grating surface, the 2nd order occurs at larger angles and so on.
Which colour do you expect to be diffracted through the largest angle? Explain your reasoning.