試題詳解

(4)A diffraction grating having 7000 lines per centimeter is illuminated normally with red light from a helium-neon gas laser. If its second-order spectral line is at 62.4°, what is the wavelength of the red laser light?
(A)650 nm
(B)671 nm
(C)633 nm
(D)648 nm
(E)635 nm