Monochromatic light from a semiconductor laser of wavelength 635 nm635\text{ nm}635 nm is incident normally on a diffraction grating with 4.0×105 lines per metre4.0 \times 10^5\text{ lines per metre}4.0×105 lines per metre.
What is the total number of bright spots that can be observed in the resulting diffraction pattern?
6
7
8
9
