The period of the grating is 7 microns. For the hydrogen spectral line with a wavelength of 486 nm to pick a greatest wavelength range that was nowhere to be overlapping spectra when illuminated with light in a given interval. The width of the grating 3 cm. The answer given in nanometers.

Detailed solution shorthand terms, formulas, laws used in the decision, the withdrawal of the calculation formula and the response.
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