A grating has 315 rulings/mm. We have to find the wavelengths in the visible spectrum which can be seen in the fifthorder diffraction.

Solution: Click For PDF Version As there are 315 rulings/mm, the grating distance d is The range of visible spectrum is . The grating equation is
The maximum wavelength that can be seen in the fifth order is determined by substituting and in the grating equation. We note that
Therefore, we conclude that wavelengths in the range can be seen in the fifthorder diffraction using the given grating. 